Federal Motor Vehicle Safety Standards; Tire Pressure Monitoring Systems; Controls and Displays

Federal RegisterApr 8, 2005

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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Parts 571 and 585

[Docket No. NHTSA 2005-20586]

RIN 2127-AJ23

Federal Motor Vehicle Safety Standards; Tire Pressure Monitoring Systems; Controls and Displays

AGENCY:

National Highway Traffic Safety Administration (NHTSA), DOT.

ACTION:

Final rule.

SUMMARY:

This final rule establishes a new Federal motor vehicle safety standard (FMVSS) requiring installation of a tire pressure monitoring system (TPMS) capable of detecting when one or more of a vehicle's tires is significantly under-inflated. This final rule responds to a mandate in the Transportation Recall Enhancement, Accountability, and Documentation (TREAD) Act. This final rule requires installation in all new light vehicles of a TPMS capable of detecting when one or more of the vehicle's tires, up to all four tires, is 25 percent or more below the manufacturer's recommended inflation pressure (placard pressure) or a minimum activation pressure specified in the standard, whichever is higher.

DATES:

Effective Date:

This final rule is effective April 8, 2005, except for subpart G of 49 CFR part 585, which is effective September 1, 2005.

Compliance Date:

Consistent with the phase-in commencing October 5, 2005, all new light vehicles must be equipped with a TPMS that meets the requirements of the standard by September 1, 2007, with the following exceptions. Vehicle manufacturers need not meet the standard's requirements for the TPMS malfunction indicator and related owner's manual language until September 1, 2007 (

i.e.

, at the end of the phase-in), and vehicles produced by final-stage manufacturers and alterers must be equipped with a compliant TPMS (including a malfunction indicator) by September 1, 2008. However, manufacturers may voluntarily certify vehicles to FMVSS No. 138 and earn carry-forward credits for compliant vehicles, produced in excess of the phase-in requirements, that are manufactured between April 8, 2005, and the conclusion of the phase-in.

Petitions for Reconsideration:

If you wish to submit a petition for reconsideration of this rule, your petition must be received by May 23, 2005.

ADDRESSES:

Petitions for reconsideration should refer to the docket number above and be submitted to: Administrator, Room 5220, National Highway Traffic Safety Administration, 400 Seventh Street, SW., Washington, DC 20590.

See the

SUPPLEMENTARY INFORMATION

portion of this document (Section VIII; Rulemaking Analyses and Notice) for DOT's Privacy Act Statement regarding documents submitted to the agency's dockets.

FOR FURTHER INFORMATION CONTACT:

For non-legal issues, you may call Mr. George Soodoo or Mr. Samuel Daniel, Office of Crash Avoidance Standards (Telephone: 202-366-2720) (Fax: 202-366-4329).

For legal issues, you may call Mr. Eric Stas, Office of the Chief Counsel (Telephone: 202-366-2992) (Fax: 202-366-3820).

You may send mail to these officials at National Highway Traffic Safety Administration, 400 Seventh Street, SW., Washington, DC 20590.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Executive Summary

A. Requirements of the Final Rule

B. Lead Time and Phase-In

C. Differences Between the Final Rule and the Notice of Proposed Rulemaking

D. Impacts of the Final Rule

II. Background

A. The TREAD Act

B. Rulemaking History Prior to the September 2004 Notice of Proposed Rulemaking

III. September 2004 Notice of Proposed Rulemaking (NPRM) and Public Comments

A. The NPRM

B. Summary of Public Comments on the NPRM

IV. The Final Rule and Response to Public Comments

A. Summary of the Requirements

B. Lead Time and Phase-In

C. Response to Public Comments by Issue

1. Low Tire Pressure Warning Lamp Activation Requirement

(a) Under-Inflation Detection Level

(b) Time Period for Low Pressure Detection

2. TPMS Malfunction Indicator Lamp (MIL) Activation Requirements

(a) Time Period for Malfunction Detection

(b) What Constitutes a TPMS Malfunction?

3. Telltale Requirements

(a) Function and Format of the Combined Low Pressure Warning/Malfunction Indicator Lamp

(b) Telltale Symbols for Low Pressure Warning and Malfunction Indication

(i) Low Pressure Warning Telltale

(ii) Malfunction Indicator Telltale

(d) Telltale Extinguishment Requirements

(e) Telltale Illumination Priority

(f) Supplemental Telltale

4. Tire-Related Issues

(a) Replacement Tires and Spare Tires

(b) Tire Reserve Load

(d) Minimum Activation Pressure

5. Owner's Manual Requirements

6. Test Procedures

(a) Calibration Time

(b) Driving Conditions

(d) Vehicle Cool-Down Period

(e) Testing with Pressures Other Than Placard Pressure

(f) System Reset

7. Lead Time and Phase-In

(a) Lead Time

(b) Phase-In Schedule

8. Small Business Impacts

9. Environmental Impacts

10. Maintenance Issues

(a) TPMS Maintenance

(b) Tire Maintenance

11. Markings for Vehicles with Direct TPMSs

12. Definitions

(a) “Tires”

(b) “Manual Reset”

13. Educational Efforts

14. Alternative Systems

15. Over-Inflation Detection

16. Temperature and Altitude Compensation

17. System Longevity

18. Harmonization

V. Benefits

VI. Costs

VII. Regulatory Alternatives

VIII. Rulemaking Analyses and Notices

I. Executive Summary

This final rule re-establishes FMVSS No. 138,

Tire Pressure Monitoring Systems

, which requires installation of a tire pressure monitoring system in light vehicles, thereby implementing a mandate in the TREAD Act. In accord with the Act, the objective of this standard is to supplement regular tire maintenance on the part of drivers by providing a warning system to alert them when one or more of a vehicle's tires become significantly under-inflated. Under-inflation of tires increases the likelihood of many different types of crashes, including those involving: (1) Skidding and/or

loss of control of the vehicle; (2) hydroplaning; (3) increases in stopping distance; (4) flat tires and blowouts, and (5) overloading of the vehicle. We anticipate that 90 percent of drivers will respond to a TPMS low tire pressure warning by re-inflating their tires to the recommended placard pressure. Once all new light vehicles are equipped with compliant TPMSs, we expect that a resulting 119-121 fatalities would be prevented each year.

As background, we note that Standard No. 138 was promulgated previously through a final rule published in the

Federal Register

on June 5, 2002 (67 FR 38704). It included two compliance options (

i.e.

, a TPMS with a four-tire, 25-percent under-inflation detection capability or a TPMS with a one-tire, 30-percent under-inflation detection capability). However, on August 6, 2003, the U.S. Court of Appeals for the Second Circuit (Second Circuit) issued its opinion in

Public Citizen

Mineta

which held that the TREAD Act requires a TPMS capable of detecting when any combination of tires, up to all four tires, is significantly under-inflated. It vacated FMVSS No. 138 and directed the agency to conduct further rulemaking. This final rule sets requirements for the TPMS standard in a manner consistent with the Second Circuit's opinion. It also responds to numerous public comments submitted in response to the agency's September 16, 2004 notice of proposed rulemaking (NPRM) (69 FR 55896).

340 F.3d 39 (2d Cir. 2003).

A. Requirements of the Final Rule

After careful consideration of all available information, including public comments, the agency has decided to retain in the final rule most of the elements of the proposed rule, with the primary changes involving the detection times for providing the low tire pressure warning and TPMS malfunction warning, modification of the minimum activation pressure values for certain light truck tires, and modifications to the standard's phase-in schedule. Although public comments on the NPRM discussed a wide variety of issues, the majority of comments focused on the topics of the TPMS malfunction indicator and the proposed schedule for lead time and phase-in, the two major aspects of the NPRM not raised at earlier stages of the TPMS rulemaking.

As reflected in the final rule, FMVSS No. 138 is a performance standard. The agency has sought to establish the standard in a fashion that both meets the need for motor vehicle safety and is also technology-neutral. Particularly in light of the rapid advances in TPMS technology in the past few years, we expect that vehicle manufacturers will have a number of technologies available for compliance purposes. Although the details of the standard, public comments, and the agency's response thereto, are discussed at length in the balance of this document, the following points summarize the key requirements of the standard.

Consistent with the Second Circuit's opinion, FMVSS No. 138 requires new passenger cars, multi-purpose passenger vehicles, trucks, and buses with a gross vehicle weight rating (GVWR) of 4,536 kg (10,000 pounds) or less, except those with dual wheels on an axle, to be equipped with a TPMS to alert the driver when one or more of the vehicle's tires, up to a total of all four tires, is significantly under-inflated. Specifically, the TPMS must warn the driver when the pressure in one or more of the vehicle's tires is 25 percent or more below the vehicle manufacturer's recommended cold inflation pressure, or a minimum level of pressure specified in the standard, whichever pressure is higher. (We note that in response to a petition for rulemaking by the Alliance of Automobile Manufacturers (Alliance) and that organization's subsequent, related comments on the NPRM, we have decided, as an interim measure, to modify our minimum activation pressure (MAP) values for some light truck tires under the standard. Once the agency conducts further safety research, we will either confirm or propose to modify these MAP requirements in response to that petition.)

If any tire drops below the standard's activation threshold, the TPMS is required to provide the low tire pressure warning by illuminating a yellow telltale within 20 minutes of additional travel within a speed range of 50-100 km/hr. This telltale must remain illuminated (and re-illuminate upon subsequent vehicle start-ups) until the under-inflation condition has been corrected. The agency has determined that the specified under-inflation threshold and the detection time will allow the TPMS to provide a timely warning that permits the driver to take corrective action before adverse consequences ensue. Thus, we believe that the low inflation pressure detection requirement of the standard both fulfills the mandate of the TREAD Act and meets the need for motor vehicle safety.

Because a small number of aftermarket and replacement tires have construction characteristics that may prevent the continued proper functioning of the TPMS when the original equipment tires are replaced and because of the difficulty in identifying those problematic tires, NHTSA has decided to require the vehicle to be certified with the tires originally installed on the vehicle at the time of initial vehicle sale. (This reflects a change from the June 2002 final rule, which required vehicle manufacturer to certify continued compliance with any optional or replacement tires of the size(s) recommended by the vehicle manufacturer.)

Nevertheless, we expect that a typical vehicle will outlast its original set of tires, and we continue to believe that it is important that drivers continue to receive the benefits of the TPMS after the vehicle's tires are replaced. Therefore, we have decided upon a different approach than that contained in the June 2002 final rule for addressing the issue of maintaining proper TPMS functionality when a vehicle's original tires are replaced. Specifically, the final rule requires the TPMS to include a malfunction indicator (provided either by a separate telltale or a combined low tire pressure/malfunction indicator telltale) that would alert the driver in situations in which the TPMS is unable to detect low tire pressure.

This malfunction indicator is required to detect incompatible replacement tires, as well as other system faults. Similar to the low tire pressure warning, the system is required to trigger a TPMS malfunction warning telltale within 20 minutes of additional travel within a speed range of 50-100 km/hr after such a malfunction occurs. Consistent with the specific requirements of the standard, this telltale must remain illuminated (and re-illuminate upon subsequent vehicle start-ups) until the TPMS malfunction has been corrected. We believe that the TPMS malfunction indicator will provide useful information to the driver regarding the long-term operability of the TPMS, thereby increasing the overall benefits of the system.

The final rule also specifies required language to be included in the vehicle owner's manual (or in writing to the first purchaser if there is no owner's manual) that describes the purpose of the low tire pressure warning telltale, the consequences of significantly under-inflated tires, the meaning of the low tire pressure telltale when it is illuminated, and corrective action to be taken. The owner's manual must also explain the presence and operation of the TPMS malfunction indicator and the potential problems associated with aftermarket and replacement tires and

rims that may prevent continued TPMS functionality. These provisions are designed to ensure that consumers are aware of the importance of regular tire maintenance and of the supporting role played by their vehicle's TPMS.

The final rule provides that compliance testing for FMVSS No. 138 will be conducted on a specific test course, namely the Southern Loop of the Treadwear Course in and around San Angelo, Texas. We believe that this approach offers several advantages. First, testing can be conducted in a timely fashion without the need to design or build a new test track. Further, this course has already been used for several years by NHTSA and the tire industry for uniform tire quality grading (UTQG) purposes. We believe that the specified test course provides an objective test that is representative of a variety of roadways and real world conditions.

B. Lead Time and Phase-In

In order to provide the public with the safety benefits of TPMSs as rapidly as possible, compliance with this final rule is set to commence on October 5, 2005, which marks the start of a two-part phase-in period. Subject to the special provisions discussed below, the phase-in schedule for FMVSS No. 138 is as follows: 20 percent of a vehicle manufacturer's light vehicles are required to comply with the standard during the period from October 5, 2005, to August 31, 2006; 70 percent during the period from September 1, 2006 to August 31, 2007, and all light vehicles thereafter.

For the reasons discussed in detail in section IV.B of this notice, we believe that it is practicable for vehicle manufacturers to meet the requirements of the phase-in discussed above, with the following exceptions. We have decided to defer vehicle manufacturers' compliance with the standard's malfunction indicator requirements and associated owner's manual language requirements until September 1, 2007. (There is no separate phase-in for the malfunction indicator requirements.) After consideration of the many public comments from vehicle manufacturers on this issue, we understand that adding the TPMS malfunction indicator will involve substantial design and production changes and that additional lead time will be required to effect those changes. In addition, our analysis demonstrates that the safety benefits associated with the early introduction of TPMSs, even without malfunction indicators, far outweigh the benefits of delaying the standard until all systems also can meet the malfunction indicator requirements. We note that manufacturers may voluntarily install a TPMS malfunction indicator prior to the mandatory compliance date.

Because our statute generally requires that a standard may not compel compliance less than 180 days after the standard is prescribed,

we have decided to postpone the starting compliance date from the NPRM's proposed date of September 1, 2005 to a date that corresponding to 180 days after publication of this final rule. However, we have decided to have the balance of the standard's phase-in coincide with traditional model year production schedules, in order to mitigate production and cost impacts.

49 U.S.C. 30111(d).

We have decided not to delay the start of compliance until Model Year 2007, as several commenters suggested. If the agency were to forego the first year of the phase-in, we would expect to lose 24 lives and to have 1,675 more injuries than would have occurred if TPMSs had been provided in vehicles, as called for in the final rule's phase-in.

Moreover, vehicle manufacturers have been well aware of the key requirements of the final rule (other then the malfunction indicator requirement), at least since the time of the Second Circuit's decision in August 2003 (if not earlier), and the September 2004 NPRM clearly conveyed the agency's intention to begin a phase-in that would coincide with Model Year (MY) 2006. Further, they did not provide any data to demonstrate that compliance with a Fall 2005 start of the phase-in would be impracticable. In addition, we believe that concerns related to lead time are either rendered moot or significantly mitigated by the final rule's allowance of both carry-forward and carry-backward credits.

As a means of maintaining a mandatory compliance date in Fall 2005, we have decided to ease implementation further by permitting carry-forward and carry-back credits. Vehicle manufacturers can earn carry-forward credits for compliant vehicles, produced in excess of the phase-in requirements, that are manufactured between the effective date of this rule and the conclusion of the phase-in.

In order to maximize the time available to earn such credits, we are making this final rule effective upon publication, although vehicle manufacturers have no certification responsibilities until the official start of the phase-in.

We note that carry-forward credits may not be used to defer the mandatory compliance date of September 1, 2007 for all covered vehicles.

With carry-backward credits, manufacturers may defer compliance with a part or all of the certification requirements under the standard for the first period of the phase-in, provided they certify a correspondingly increased number of vehicles during the second period of the phase-in. We believe that permitting carry-backward credits would not impact the overall safety benefits of the final rule because the same number of vehicles would be subject to compliance certification, although the distribution may vary over the model years of the phase-in.

On other topics related to the phase-in, NHTSA has decided to exclude multi-stage manufacturers and alterers from the requirements of the phase-in and to extend by one year the time for compliance by those manufacturers (

i.e.

, until September 1, 2008). The final rule also excludes small volume manufacturers (

i.e.

, manufacturers producing less than 5,000 vehicles for sale in the U.S. market in one year) from the phase-in, requiring vehicles produced by such manufacturers to comply with the standard on September 1, 2007.

C. Differences Between the Final Rule and the Notice of Proposed Rulemaking

As noted above, NHTSA has decided to adopt most of the provisions contained in the NPRM as part of this final rule. The main differences between the NPRM and the final rule involve the phase-in schedule for the standard, the requirements for low tire pressure and TPMS malfunction detection time, changes to the minimum activation pressure for certain light truck tires, and modifications to the vehicle owner's manual requirements. A number of minor technical modifications also were incorporated in the final rule in response to public comments on the NPRM. All of these changes and their rationale are discussed fully in the balance of this document. However, the following points briefly describe the main differences between the NPRM and this final rule.

• In the final rule, we have decided to increase the time period for the TPMS to detect low tire pressure to 20 minutes. The NPRM had proposed a time period of 10 minutes for the TPMS to detect low tire pressure and illuminate the warning telltale.

• The final rule specifies a time period for the TPMS to detect a system malfunction and to illuminate the TPMS malfunction indicator (20 minutes) and acknowledged that many systems may require vehicle motion to detect a malfunction. The NPRM had been silent on these matters.

• The agency has decided to require the words (“ TPMS”) for the dedicated TPMS malfunction telltale, rather than the symbol proposed in the NPRM. We have also lengthened the time period for flashing of the combined low tire pressure/malfunction indicator telltale from the proposed one minute to a period of 60-90 seconds.

• The final rule has adopted minimum activation pressures for light truck Load Range “D” and “E” tires of 35 psi (240 kPa), which is different from the values in the NPRM. (However, the agency has stated that it is conducting further research in this area and that it may revisit this issue.)

• The final rule's requirements for the specified statement in the owner's manual regarding the TPMS have changed from the NPRM. Specifically, these changes include clarification that both aftermarket tires and rims may affect the TPMS's continued functionality, tailoring of the language to reflect the two options for the TPMS malfunction indicator, stressing of the driver's ongoing responsibility for regular tire maintenance, and alerting consumers that some replacement tires may call for an inflation pressure different than what is reflected on the vehicle placard.

• In the final rule's test procedures, we have deleted the NPRM's test requirements related to system reset. We have decided that this provision is impracticable, based upon how most resets operate, and unnecessary, because vehicles equipped with a TPMS reset normally include instructions for the proper use of the reset feature as part of the owner's manual.

The final rule's phase-in schedule has changed from the NPRM's 50-90-100% requirement to a 20-70-100% requirement. In another change from the NPRM, vehicle manufacturers are not required to meet the standard's requirements for the TPMS malfunction indicator (and associated owner's manual requirements) until the end of the phase-in (

i.e.

, September 1, 2007).

• The final rule permits vehicle manufacturers to elect to use carry-backward credits in meeting the phase-in requirements under the standard. That provision was not present in the NPRM.

• The final rule extends the compliance date for final-stage manufacturers and alterers by one year (

i.e.

, to September 1, 2008). The NPRM had proposed to require compliance for these manufacturers' production by September 1, 2007.

D. Impacts of the Final Rule

Depending upon the technology chosen for compliance, the agency estimates that the total quantified safety benefits from reductions in crashes due to skidding/loss of control, stopping distance, flat tires, and blowouts, will be 119-121 fatalities prevented and 8,373-8,568 injuries prevented or reduced in severity each year, once all light vehicles meet the TPMS requirement.

Additional benefits are expected to accrue from the final rule as a result of improved fuel economy ($19.07-$23.08 per vehicle over its lifetime), longer tread life ($3.42-$4.24 per vehicle), and property damage savings and travel delay savings from avoided crashes ($7.70-$7.79 per vehicle) (assuming a three-percent discount rate).

The agency estimates that the average cost per vehicle to meet the standard's requirements to be $48.44-$69.89, depending upon the technology chosen for compliance. Since approximately 17 million light vehicles are produced for sale in the U.S. each year, the total annual vehicle cost is expected to range from approximately $823-$1,188 million per year.

II. Background

A. The TREAD Act

Congress enacted the TREAD Act

on November 1, 2000. Section 13 of that Act

required the Secretary of Transportation, within one year of the statute's enactment, to complete a rulemaking “to require a warning system in new motor vehicles to indicate to the operator when a tire is significantly under inflated.” Section 13 also required the regulation to take effect within two years of the completion of the rulemaking. Responsibility for this rulemaking was delegated to NHTSA.

Pub. L. 106-414, 114 Stat. 1800 (2000).

See

49 U.S.C. 30123 note (2003).

B. Rulemaking History Prior to the September 2004 Notice of Proposed Rulemaking

FMVSS No. 138,

Tire Pressure Monitoring Systems

, has had a protracted regulatory history. The following discussion briefly summarizes the key milestones in the TPMS rulemaking process.

Today's final rule was preceded by an initial NPRM on July 26, 2001 (66 FR 38982). After considering public comments received on that NPRM, NHTSA prepared a final rule, which was submitted to the Office of Management and Budget (OMB) for review. After reviewing the draft final rule, OMB returned it to NHTSA for further consideration, with a letter explaining the reasons for doing so, on February 12, 2002.

On June 5, 2002, NHTSA published a final rule for TPMS (67 FR 38704). Consistent with the OMB return letter, the agency divided the TPMS final rule into two parts, because it decided to defer its decision as to which long-term performance requirements for TPMS would best satisfy the mandate of the TREAD Act. This deferral was intended to allow the agency time to consider additional data on the effect and performance of TPMSs currently in use.

The June 5, 2002 final rule provided two compliance options during the interim period (

i.e.

, between November 1, 2003 and October 31, 2006). Under the first compliance option, vehicle manufacturers would have been required to equip their light vehicles (

i.e.

, those with a GVWR of 4,536 kg (10,000 pounds) or less) with TPMSs to warn the driver when the pressure in any single tire or in each tire in any combination of tires, up to a total of four tires, is 25 percent or more below the vehicle manufacturer's recommended cold inflation pressure for the tires, or a minimum level of pressure specified in the standard, whichever pressure is higher. Under the second compliance option, the vehicle's TPMS would have been required to warn the driver when the pressure in any single tire is 30 percent or more below the vehicle manufacturer's recommended cold inflation pressure for the tires, or a minimum level of pressure specified in the standard, whichever pressure is higher.

The minimum levels of pressure were the same for both compliance options.

The two compliance options were outgrowths of the alternative sets of requirements proposed in the initial NPRM. In response to comments indicating that current indirect TPMSs could not meet the NPRM's proposed detection requirements, the agency adopted a one-tire, 30-percent option that would have permitted indirect TPMSs to be used during the phase-in period.

NHTSA received 13 petitions

for reconsideration of the June 2002 final rule, raising a variety of issues.

There are two types of TPMSs currently available, direct TPMSs and indirect TPMSs. Direct TPMSs have a pressure sensor in each wheel that transmits pressure information to a receiver. In contrast, indirect TPMSs do not have tire pressure sensors, but instead rely on the wheel speed sensors, typically a component of an anti-lock braking system, to detect and compare differences in the rotational speed of a vehicle's wheels, which correlate to differences in tire pressure.

We anticipate that new types of TPMS technology may be developed in the future that will be capable of meeting the standard's requirements. For example, such systems might incorporate aspects of

both direct and indirect TPMSs (

i.e.

, hybrid systems). In concert with TPMS suppliers, tire manufacturers might be able to incorporate TPMS sensors directly into the tires themselves. In issuing a performance standard, NHTSA is cognizant of and seeks to encourage technological innovation.

However, after issuance of the June 2002 final rule, Public Citizen, Inc., New York Public Interest Research Group, and the Center for Auto Safety filed a suit challenging certain aspects of the TPMS regulation. The Court of Appeals for the Second Circuit issued its opinion in

Public Citizen, Inc.

Mineta

on August 6, 2003, which held that the agency's adoption in the standard of a one-tire, 30-percent compliance option was “contrary to the intent of the TREAD Act and, in light of the relative shortcomings of indirect systems, arbitrary and capricious.”

The Court found that the TREAD Act unambiguously mandates TPMSs capable of monitoring each tire, up to a total of four tires, effectively precluding the one-tire, 30-percent option, or any similar option that cannot detect under-inflation in any combination of tires up to four tires.

340 F.3d 39, 54 (2d Cir. 2003).

Ultimately, the Court vacated the standard (FMVSS No. 138) in its entirety and directed the agency to issue a new rule consistent with its August 6, 2003 opinion. NHTSA published a final rule in the

Federal Register

on November 20, 2003, vacating FMVSS No. 138 (68 FR 65404). With the standard vacated, that notice clarified that, at that point in time, vehicle manufacturers had no certification or reporting responsibilities.

In light of the foregoing, NHTSA commenced rulemaking efforts to reestablish FMVSS No. 138 in a manner consistent with the Court's opinion and responsive to the issues raised in earlier petitions for reconsideration, the majority of which remained relevant. To this end, the agency issued a second NPRM on September 16, 2004 (69 FR 55896) (discussed immediately below) and obtained and considered public comments on that NPRM, actions leading to this latest final rule for TPMS.

For a more complete discussion of this earlier period of the regulatory history of the TPMS rulemaking, readers should consult the June 5, 2002 final rule and the September 16, 2004 NPRM.

III. September 2004 Notice of Proposed Rulemaking (NPRM) and Public Comments

A. The NPRM

As noted above, NHTSA published an NPRM on September 16, 2004 that proposed to re-establish FMVSS No. 138,

Tire Pressure Monitoring Systems,

in a manner consistent with the Court's opinion. Specifically, it proposed to require passenger cars, multipurpose passenger vehicles, trucks, and buses with a GVWR of 4,536 kg (10,000 pounds) or less, except those with dual wheels on an axle, to be equipped with a TPMS to alert the driver when one or more of the vehicle's tires, up to all four of its tires, are significantly under-inflated. The NPRM was drafted so as to be technology-neutral, so as to permit compliance with any available TPMS technology that meets the performance requirements.

The NPRM included the following points, which highlighted the key provisions of the proposed requirements.

• The TPMS would be required to warn the driver when the pressure in one or more of the vehicle's tires, up to a total of four tires, is 25 percent or more below the vehicle manufacturer's recommended cold inflation pressure for the tires, or a minimum level of pressure specified in the standard, whichever pressure is higher.

• Vehicle manufacturers would be required to certify vehicle compliance under the standard with the tires installed on the vehicle at the time of initial vehicle sale.

The NPRM noted that some vehicle manufacturers authorize their dealers to replace the vehicle's factory-installed tires with other tires, including ones with a different size and/or recommended cold tire inflation pressure. The NPRM stated that the TPMS would have to perform properly with any such tires, because the vehicle could be equipped with those tires at the time of initial sale. Of course, the manufacturer would not have that responsibility if the dealer installed other tires without manufacturer authorization. However, the dealer would violate the Motor Vehicle Safety Act if it installed tires on a new vehicle that prevented the TPMS from functioning properly. See 49 U.S.C. 30112(a).

• The TPMS would be required to include a low pressure telltale (yellow) that must remain illuminated as long as any of the vehicle's tires remains under-inflated and the vehicle's ignition locking system is in the “On” (“Run”) position. The telltale would be required to extinguish when all of the vehicle's tires cease to be significantly under-inflated. The TPMS's low tire pressure warning telltale would be required to perform a bulb-check at vehicle start-up.

• The TPMS also would be required to include a malfunction indicator to alert the driver when the system is non-operational and, thus, unable to provide the required low tire pressure warning. The NPRM proposed that TPMS malfunction could be indicated by either:

(1) Installing a separate, dedicated telltale (yellow) that illuminates upon detection of the malfunction and remains continuously illuminated as long as the ignition locking system is in the “On” (“Run”) position and the situation causing the malfunction remains uncorrected, or

(2) Designing the low tire pressure telltale so that it flashes for one minute when a malfunction is detected, after which the telltale would remain illuminated as long as the ignition locking system is in the “On” (”Run”) position. This flashing and illumination sequence would be repeated upon each subsequent vehicle start-up until the situation causing the malfunction has been corrected.

If the option for a separate telltale is selected, the TPMS malfunction telltale would be required to perform a bulb-check at vehicle start-up.

• The TPMS would not be required to monitor the spare tire (if provided) either when it is stowed or when it is installed on the vehicle.

• For vehicles certified under the standard, vehicle manufacturers would be required to provide in the owner's manual an explanation of the purpose of the low tire pressure warning telltale, the potential consequences of significantly under-inflated tires, the meaning of the telltale when it is illuminated, and what actions drivers should take when the telltale is illuminated. Vehicle manufacturers also would be required to provide a specified statement in the owner's manual regarding: (1) Potential problems related to compatibility between the vehicle's TPMS and various replacement tires, and (2) the presence and operation of the TPMS malfunction indicator.

The NPRM proposed requirements for covered vehicles manufactured on or after September 1, 2005 (

i.e.

, MY 2006), subject to the following phase-in schedule: 50 percent of a vehicle manufacturer's light vehicles would be required to comply with the standard during the first year (September 1, 2005 to August 31, 2006); 90 percent during the second year (September 1, 2006 to August 31, 2007); and all vehicles thereafter.

The NPRM stated that in order to encourage early compliance, the agency was proposing to permit carry-forward credits for vehicles that are certified as complying with the standard and that are manufactured on or after the

effective date of the final rule. However, under the proposal, beginning September 1, 2007, all covered vehicles would be required to comply with the standard, without regard to any earlier carry-forward credits.

We proposed to exclude from the phase-in requirements final stage manufacturers, alterers, and small volume manufacturers (SVMs). The NPRM also proposed phase-in reporting requirements consistent with the proposed phase-in schedule.

B. Summary of Public Comments on the NPRM

NHTSA received comments on the September 16, 2004 NPRM from a variety of interested parties including 10 TPMS manufacturers,

13 automobile manufacturers and their trade associations,

seven tire manufacturers and their trade associations,

two public interest groups,

and six other interested organizations.

Comments were also received from 24 individuals. All of these comments may be found in Docket No. NHTSA-2004-19054.

Comments were received from the following TPMS manufacturers: (1) ALPS Automotive, Inc.; (2) Aviation Upgrade Technologies; (3) BERU Corporation; (4) Continental Teves, Inc.; (5) Emtop Ltd.; (6) EnTire Solutions, LLC; (7) ETV Corporation Pty Limited; (8) MLHO, Inc.; (9) NIRA Dynamics AB, and (10) Schrader Electronics Ltd.

Comments were received from the following automobile manufacturers and related trade associations: (1) Alliance of Automobile Manufacturers; (2) American Suzuki Motor Corporation; (3) Association of International Automobile Manufacturers, Inc.; (4) BMW of North America, LLC; (5) DaimlerChrysler Corporation; (6) DaimlerChrysler and Mercedes-Benz U.S.A.; (7) Fuji Heavy Industries USA, Inc. (makers of Subaru vehicles); (8) General Motors North America; (9) Honda Motor Co., Ltd. and American Honda Motor Co., Inc.; (10) Hyundai American Technical Center, Inc./Kia Motors Corporation; (11) Mitsubishi Motors R&D of America, Inc.; (12) Nissan North America, Inc.; (13) Porsche Cars North America, Inc., and (14) Volkswagen/Audi.

Comments were received from the following tire manufacturers and related trade associations: (1) European Tyre and Rim Technical Organisation; (2) Japan Automobile Tyre Manufacturers Association, Inc.; (3) Rubber Manufacturers Association; (4) Sumitomo Rubber Industries; (5) The Tire Rack; (6) Tire and Rim Association, Inc., and (7) Tire Industry Association.

Comments were received from the following public interest groups: (1) Advocates for Highway and Auto Safety, and (2) Public Citizen.

Comments were received from the following other interested manufacturers, trade associations, and groups: (1) American Automobile Association; (2) the European Communities; (3) Fairfax County Public Schools; (4) GE Infrastructure Sensing; (5) National Automobile Dealers Association, and (6) Specialty Equipment Market Association.

The commenters raised a variety of issues with the proposed requirements, including ones related to the low tire pressure warning lamp activation, the TPMS malfunction indicator lamp, the TPMS low pressure and MIL telltales, test procedures, minimum activation pressure requirements, the need for a tire reserve load, owner's manual requirements, TPMS operation with replacement tires/spare tires, lead time and phase-in, and other topics. The following discussion summarizes the main issues raised by these public comments and the positions expressed on these topics. A more complete discussion of the public comments is provided under Section IV.C, which provides an explanation of the agency rationale for the requirements of the final rule and addresses related public comments by issue.

Low Tire Pressure Warning Lamp Activation Requirements

Regarding the activation requirements for the low tire pressure warning lamp, commenters raised concerns related to the NPRM's proposed under-inflation detection level, as well as the proposed 10-minute time period for under-inflation detection. Public interest groups and certain other commenters urged NHTSA to adopt a more stringent threshold for under-inflation detection (ranging from 15-20 percent below placard pressure). These commenters argued that existing technologies (

i.e.

, direct TPMSs) can detect and warn the driver at lesser levels of under-inflation, thereby permitting drivers more time to take corrective action and maximizing the benefits provided by the system.

The tire industry also urged NHTSA to adopt a more stringent under-inflation detection threshold, with a trigger point tied to the vehicle placard pressure and the Gross Axle Weight Rating (GAWR). Specifically, the comment of TIA stated that the under-inflation detection warning should be triggered at 1-2 psi below the vehicle's recommended cold tire inflation pressure or at an inflation level where the tires can no longer carry the vehicle weight, whichever is higher. Other commenters suggested that the under-inflation detection threshold should take into account various vehicle loading conditions.

Vehicle manufacturers did not comment on the under-inflation detection level, which suggests that they do not object to that aspect of the NPRM.

Regarding the NPRM's proposed 10-minute time period for low tire pressure detection, vehicle manufacturers generally recommended extending that time period, arguing that even direct systems would require additional time to detect, confirm, and relay a warning about a significantly under-inflated tire. Comments from vehicle manufacturers also suggested that in order to be technology-neutral and to permit vehicle certification with indirect systems, the under-inflation detection time should be extended in situations where the vehicle has two, three, or four significantly under-inflated tires; those comments argued that there is not a safety need for rapid detection in such cases, where under-inflation is likely to result from diffusion over a considerable period of time.

Public interest groups, the European Communities (EC), and certain other industry commenters argued that the proposed 10-minute detection time period is too long and that it would allow vehicles to continue to travel in a potentially unsafe condition without a warning. These comments suggested that such situations are unnecessary because technology currently exists that would permit a shorter detection time.

TPMS MIL Activation Requirements

Regarding the time period for malfunction detection, vehicle manufacturers stated their concern regarding the absence in the NPRM of an expressed time period for the TPMS to detect a malfunction and to illuminate the TPMS MIL. Commenters stated that immediate detection, as implied by the NPRM, is not technically possible and that in most cases, the vehicle must be driven in order to detect a malfunction. Several commenters stated that TPMSs cannot detect malfunctions any faster than the system can detect low tire pressure (because the same subsystems are involved) and that the same durational parameters should be set for both functions (with suggestions ranging from 20-30 minutes).

A number of manufacturers commented that the proposed TPMS malfunction requirements are overly broad and are in need of modification. Specific commenters asserted that TPMSs would have difficulties detecting or reporting various types of malfunctions.

One commenter raised the issue of MIL disablement (or suppression) in situations where the TPMS sending units have been removed as a result of the replacement of the original equipment tires and rims with aftermarket components that are not compatible with the direct-sensing TPMS. (The NPRM made no provision for MIL disablement.)

Telltale Requirements

A number of commenters discussed the issue of how the TPMS MIL would operate, particularly when it is combined with the low tire pressure warning telltale. Some commenters,

primarily representing vehicle manufacturers, argued that the MIL requirements are design-restrictive and may impose unnecessary costs. Those commenters requested flexibility in providing the malfunction warning through a variety of means (

e.g.

, text messaging and audible warnings), provided that the warning is explained in the vehicle owner's manual.

Several commenters expressed concern about how the malfunction warning would be provided to the driver in a combined telltale. Some commenters argued that flashing should be used to indicate low tire pressure; some argued that flashing should be used to indicate malfunction; some argued that the flashing sequence should be longer, and still others argued that any sort of flashing may be confusing to drivers.

Public interest groups generally favored requiring a separate telltale to indicate TPMS malfunction, in order to provide a clear message to drivers. However, manufacturers commented that separate telltales are unnecessary, add cost, and consume valuable space on the instrument panel that could be used to provide other safety messages.

Commenters overwhelmingly recommended that NHTSA reconsider its proposed symbol to indicate a TPMS malfunction, which was considered to be confusing, and a variety of alternatives were suggested. Some commenters expressed support for only permitting a low tire pressure telltale that indicates which tire is under-inflated, because such symbol is both more recognizable and offers enhanced information to the driver.

Regarding telltale color, some manufacturers recommended permitting the low tire pressure telltale to change color (

e.g.

, from yellow to red) to indicate when under-inflation has progressed to a dangerously low level, as determined by the vehicle manufacturer. Commenters also raised the issue of the color of the TPMS MIL, with some recommending yellow and others recommending red.

In their comments, manufacturers also raised issues related to extinguishment of the TPMS telltales. For example, concerns were raised regarding the possibility of a TPMS reset button extinguishing the telltale before the underlying problem (

i.e.

, low tire pressure or system malfunction) has been corrected. Others suggested that the final rule should specify that tires must be re-inflated to a level at least 10 percent above the warning threshold before the TPMS low pressure telltale would extinguish.

Another topic raised by commenters related to the TPMS combined telltale involved requests for the final rule to set an illumination priority for the low tire pressure and TPMS malfunction warnings. Commenters did not agree as to which warning should take precedence.

Tire-Related Issues

Another major area of comment involved tire issues. Regarding the issue of the NPRM's proposed approach for TPMS operation with replacement and spare tires, public interest groups generally objected to the agency's tentative decision to require compliance certification with the tires originally installed on the vehicle, but to require a malfunction indicator to indicate to the driver when replacement tires have been installed on the vehicle which prevent the continued proper functioning of the TPMS. Those commenters suggested that the TPMS should either be required to function with all replacement tires and original equipment (OE) full-sized spare tires (so as to provide continuing operational benefits to consumers) or that there should be ongoing efforts to make the public aware of those tires which have been found to prevent proper TPMS functioning.

Comments from the tire industry also supported a requirement for the TPMS to operate with replacement tires, particularly in light of those tires' prevalence in the marketplace. Those commenters further argued that vehicle manufacturers should be required to provide affordable access to TPMS service information to all tire dealers and service providers. Other commenters expressed concern regarding the impact the proposed rule would have on small businesses.

The tire industry recommended that the final rule should include a tire pressure reserve requirement in order to ensure that the vehicle can safely carry the vehicle maximum load, even if the tires are under-inflated by 25 percent below placard pressure. Otherwise, commenters argued that the vehicle's tires may fall below the level designated in the tire industry's load/pressure tables but still not trigger a low pressure warning from the TPMS. These commenters were especially concerned that this situation could lead to increased instances of tire failure, particularly if drivers come to rely on the TPMS as a substitute for regular tire maintenance. Moreover, the Tire and Rim Association (TRA) stated its intention to modify its 2005 Year Book to provide additional instruction for manufacturers of TPMS-equipped vehicles.

The Alliance commented that the NPRM's proposed Table 1, which specifies minimum activation pressures for different tires, should be modified for Load Range “C,” “D,” and “E” light truck (LT) tires. According to the Alliance, the MAPs currently contained in Table 1 do not allow such tires to be used across the safe operating ranges of inflation pressures for which loads are specified in the TRA Yearbooks. The Alliance argued that unless corrective action is taken, vehicle manufacturers could face costly vehicle redesigns or be forced to substitute less capable tires in certain vehicle applications.

Owner's Manual Requirements

Several commenters suggested modifications to the NPRM's proposed language related to TPMSs for the vehicle owner's manual. One comment involved allowing vehicle manufacturers discretion to tailor the owner's manual statement to the system installed on the vehicle, provided that certain basic topics were addressed. Other comments included clarifying the discussion of permissible telltale formats, of proper pressures for replacement wheel/tire combinations, and of ongoing driver responsibility for maintaining proper tire inflation pressure.

Test Procedures

Commenters raised a number of issues related to the NPRM's proposed test conditions and procedures. The issue of calibration time was raised, with at least one manufacturer commenter suggesting that no calibration period is necessary, and other manufacturer commenters arguing that the NPRM's proposed 20-minute calibration time should be extended to 30 minutes or one hour.

Comments from the tire industry recommended that the test conditions and performance parameters in the final rule should be expanded to capture a fuller range of real world driving conditions. Specifically, these comments recommended expanding the proposed ambient temperature range to include colder and warmer temperatures, testing under slippery road conditions, and expanding the vehicle speed range to include both slower and faster speeds.

Commenters also offered suggestions pertaining to the test procedures for TPMS MIL activation, which would implement their recommendations regarding the types of malfunctions the system should be required to detect and how quickly they should be detected.

Manufacturers also commented on the proposed cool-down period of up to one hour, as contained in S6(e) of the proposed test procedures. The Alliance recommended reducing the cool-down period to five minutes or less, arguing that in certain cases, tires deflated during testing when cold may warm up to a point above the warning threshold before the TPMS has time to detect a significantly under-inflated tire. Other commenters made similar arguments and recommended adding additional pressure checks to the test procedures to ensure that the pressure level has been set accurately during testing.

Other commenters urged NHTSA to modify the test procedures to recognize that testing may need to be conducted with a pressure other than placard pressure in order to properly match the load on the tires. These comments suggested that the owner's manual should be consulted in order to select the proper pressure under certain situations.

Several commenters also raised issues regarding use of a system reset feature during testing, including use in situations where the driver switches between summer and winter tires.

Lead Time and Phase-In

In general, most of the vehicle manufacturers that commented on the NPRM requested additional lead time and a modified phase-in schedule, arguing that more time is necessary to incorporate TPMS technologies into their new vehicle production processes. Most vehicle manufacturer commenters recommended a two-year phase-in, with an initial compliance date beginning on September 1, 2006. Furthermore, vehicle manufacturers universally commented that it would not be possible to incorporate the TPMS MIL until September 1, 2007.

In contrast, public interest groups expressed support for the NPRM's compliance schedule, as proposed.

Other Issues

Commenters also raised a variety of other issues in response to the NPRM. These included small business impacts, environmental impacts, maintenance issues, markings on vehicles equipped with direct TPMSs, definitions, educational efforts, alternative systems, over-inflation detection, temperature and altitude compensation, system longevity, and harmonization. Comments on each of these issues will be described and addressed in section IV.C of this notice.

IV. The Final Rule and Response to Public Comments

A. Summary of the Requirements

After careful consideration of public comments on the NPRM, this final rule re-establishes FMVSS No. 138,

Tire Pressure Monitoring Systems,

in a manner consistent with the Second Circuit's opinion. Specifically, it requires passenger cars, multi-purpose passenger vehicles, trucks, and buses with a GVWR of 4,536 kg (10,000 pounds) or less, except those with dual wheels on an axle, to be equipped with a TPMS to alert the driver when one or more of the vehicle's tires, up to all four of its tires, is significantly under-inflated. Subject to the phase-in schedule and the exceptions below, compliance with the requirements of the final rule commences for covered vehicles manufactured on or after October 5, 2005 (

i.e.

, MY 2006). The standard is intended to be technology-neutral, so as to permit compliance with any available TPMS technology that meets the standard's performance requirements.

The following points highlight the key provisions of the final rule.

• The TPMS is required to detect and to provide a warning to the driver within 20 minutes of when the pressure of one or more of the vehicle's tires, up to a total of four tires, is 25 percent or more below the vehicle manufacturer's recommended cold inflation pressure for the tires, or a minimum level of pressure specified in the standard, whichever pressure is higher. These minimum activation pressures are included in Table 1 of FMVSS No. 138.

We note that the Alliance of Automobile Manufacturers submitted a Petition for Rulemaking on April 29, 2003 that asks NHTSA to make certain changes to the MAPs in Table 1 (

see

Docket No. NHTSA-2000-8572-265). For a more complete discussion of the MAP issue raised by the Alliance, see section IV.C.4.d of this document. NHTSA is in the process of evaluating the issues raised in the Alliance petition. However, we have decided to modify the values in Table 1 pertaining to Load Range “D” and “E” tires, pending completion of our analysis.

• Vehicle manufacturers must certify vehicle compliance under the standard with the tires installed on the vehicle at the time of initial vehicle sale.

We note that some vehicle manufacturers authorize their dealers to replace the vehicle's factory-installed tires with other tires, including ones with a different size and/or recommended cold tire inflation pressure. The TPMS must perform properly with any such tires, because the vehicle could be equipped with those tires at the time of initial sale. Of course, the manufacturer would not have that responsibility if the dealer installed other tires without manufacturer authorization.

• The TPMS must include a low tire pressure warning telltale

(yellow) that must remain illuminated as long as any of the vehicle's tires remain significantly under-inflated and the vehicle's ignition locking system is in the “On” (“Run”) position.

The TPMS's low tire pressure warning telltale must perform a bulb-check at vehicle start-up.

As part of this final rule, we are adding two versions of the TPMS low tire pressure telltale and a TPMS malfunction telltale to Table 2 of FMVSS No. 101,

Controls and Displays.

The regulatory text in this final rule incorporates the TPMS telltales in Table 2, as that table currently exists in the Code of Federal Regulations. However, we note that NHTSA published an NPRM in the

Federal Register

on September 23, 2003 that proposes to update and to expand FMVSS No. 101 (68 FR 55217). Publication of the present version of Table 2 here is not intended to suggest a change in approach to the ongoing FMVSS No. 101 rulemaking. We anticipate incorporating the TPMS telltales in a revised Table 2, once a final decision is reached on updating Standard No. 101.

We note that if a vehicle manufacturer elects to install a low tire pressure telltale that indicates which tire is under-inflated, the telltale must correctly identify the under-inflated tire.

See

S4.3.2.

• The TPMS must also include a TPMS malfunction indicator to alert the driver when the system is non-operational, and thus unable to provide the required low tire pressure warning.

The TPMS malfunction indicator must detect a malfunction within 20 minutes of occurrence and provide a warning to the driver. This final rule provides two options by which vehicle manufacturers may indicate a TPMS malfunction:

We note that the TPMS telltale(s) may be incorporated as part of a reconfigurable display, provided all requirements of the standard are met.

(1) Installation of a separate, dedicated telltale (yellow) that illuminates upon detection of the malfunction and remains continuously illuminated as long as the ignition locking system is in the “On” (“Run”) position and the situation causing the malfunction remains uncorrected, or

(2) Designing the low tire pressure telltale so that it flashes for a period of at least 60 seconds and no longer than 90 seconds when a malfunction is detected, after which the telltale must remain continuously illuminated as long as the ignition locking system is in the “On” (“Run”) position. This flashing and illumination sequence must be repeated upon each subsequent vehicle start-up until the situation causing the malfunction has been corrected.

If the option for a separate telltale is selected, the TPMS malfunction telltale must perform a bulb-check at vehicle start-up.

• The TPMS is not required to monitor the spare tire (if provided),

either when it is stowed or when it is installed on the vehicle.

• For vehicles certified under the standard, vehicle manufacturers must provide in the owner's manual a specified statement explaining the purpose of the low tire pressure warning telltale, the potential consequences of significantly under-inflated tires, the meaning of the telltale when it is illuminated, and what actions drivers should take when the telltale is illuminated. Vehicle manufacturers also must provide a specified statement in the owner's manual regarding: (1) potential problems related to compatibility between the vehicle's TPMS and various replacement or alternate tires and wheels, and (2) the presence and operation of the TPMS malfunction indicator. For vehicles that do not come with an owner's manual, the required information must be provided in writing to the first purchaser at the time of initial vehicle sale.

B. Lead Time and Phase-In

As discussed in the NPRM, the Second Circuit's decision vacating FMVSS No. 138 necessitated a change in the standard's phase-in schedule in order to ensure the practicability of the standard's implementation, particularly for those manufacturers that had intended to certify to the June 5, 2002 final rule's one-tire, 30-percent option. Responses to the agency's September 9, 2003 Special Orders to 14 vehicle manufacturer and 13 TPMS suppliers demonstrated that in anticipation of the start of the phase-in under the June 2002 final rule, most vehicle manufacturers were moving aggressively toward installation of TPMSs capable of meeting the four-tire, 25-percent detection requirement, although some were not. The information provided by TPMS suppliers indicated sufficient capacity to supply TPMSs with a four-tire, 25-percent detection capability in quantities that would easily meet the phase-in requirements. Accordingly, in the NPRM, the agency proposed that 50 percent of a vehicle manufacturer's light vehicles would be required to comply with the standard during the first year (September 1, 2005 to August 31, 2006); 90 percent during the second year (September 1, 2006 to August 31, 2007); and all vehicles thereafter.

In public comments on the NPRM, vehicle manufacturers argued that they would not be able to meet the standard's requirements given the proposed lead time and phase-in schedule. Most of their concerns involved the TPMS malfunction indicator, a newly proposed requirements which manufacturers uniformly agreed would necessitate significant engineering and vehicle design efforts and corresponding production changes. Vehicle manufacturers stated that they could meet the TPMS MIL requirements (and associated owner's manual requirements) by September 1, 2007. More generally, vehicle manufacturers commented that, setting aside the issue of the MIL requirements, the phase-in schedule nevertheless may be too aggressive.

We acknowledge that the TPMS MIL represents a new requirement impacting TPMS design and functionality and that vehicle manufacturers may require additional time to incorporate the MIL into their production processes. However, we do not believe that implementation of the entire standard should be delayed until technical changes related to the TPMS MIL can be fully resolved, because that would deny the public the safety benefits of TPMSs in the meantime. Accordingly, we believe that it is preferable to move rapidly to implement the standard, but to delay the compliance date only for the TPMS MIL requirements and associated requirements in the owner's manual.

In light of the above and subject to the vehicle manufacturer option for carry-backward credits discussed below, NHTSA has decided to adopt the following phase-in schedule: 20 percent of a vehicle manufacturer's light vehicles are required to comply with the standard during the period from October 5, 2005, to August 31, 2006; 70 percent during the period from September 1, 2006 to August 31, 2007, and all light vehicles thereafter. However, vehicle manufacturers are not required to comply with the requirements related to the TPMS malfunction indicator (including associated owner's manual requirements) until September 1, 2007; however, at that point, all covered vehicles must meet all relevant requirements of the standard (

i.e.

, no additional phase-in for MIL requirements). The final rule includes phase-in reporting requirements consistent with the phase-in schedule discussed above.

Small volume manufacturers (

i.e.

, those manufacturers producing fewer than 5,000 vehicles for sale in the U.S. per year during the phase-in period) are not subject to the phase-in requirements, but their vehicles must meet the requirements of the standard beginning September 1, 2007.

Consistent with the policy set forth in NHTSA's February 14, 2005 final rule on certification requirements for vehicles built in two or more stages and altered vehicles (70 FR 7414), final-stage manufacturers and alterers must certify compliance for covered vehicles manufactured on or after September 1, 2008. However, final-stage manufacturers and alterers may voluntarily certify compliance with the standard prior to this date.

NHTSA has decided to permit vehicle manufacturers to earn carry-forward credits for compliant vehicles, produced in excess of the phase-in requirements, that are manufactured between the effective date of this rule and the conclusion of the phase-in. These carry-forward credits could be used during the phase-in, but they could not be used to delay compliance certification for vehicles produced after the conclusion of the phase-in. Except for vehicles produced by final-stage manufacturers and alterers (who receive an additional year for compliance), all covered vehicles must comply with FMVSS No. 138 on September 1, 2007, without use of any carry-forward credits.

Furthermore, we have determined that there is good cause to make this final rule effective upon publication so that vehicle manufacturers would have a standard in effect to which they may certify vehicles for purposes of early, voluntary compliance and to maximize the time for earning carry-forward credits. We explicitly note that vehicle manufacturers have no mandatory compliance responsibilities under the standard until the start of the phase-in.

To further ease implementation, we have decided to also provide carry-backward credits, whereby vehicle manufacturers may defer compliance with a part or all of the certification requirements for the first period of the phase-in, provided that they certify a correspondingly larger percentage of vehicles under the standard during the second period of the phase-in. We believe that permitting carry-backward credits would not impact the overall safety benefits of the final rule, because the same number of vehicles would be subject to compliance certification, although the distribution may vary over the model years of the phase-in. Corresponding changes have been added to the regulatory text of both FMVSS No. 138, as well as the TPMS phase-in requirements contained in 49 CFR Part 585.

C. Response to Public Comments by Issue

As noted previously, public comments on the September 2004 NPRM for TPMS raised a variety of issues with the NPRM's proposed requirements. Each of these topics will be discussed in turn, in order to explain

how these comments impacted the agency's determinations in terms of setting requirements for this final rule.

1. Low Tire Pressure Warning Lamp Activation Requirement

(a) Under-Inflation Detection Level. The NPRM proposed to require the TPMS to illuminate a low tire pressure warning telltale not more than 10 minutes after the inflation pressure in one or more of the vehicle's tires, up to a total of four tires, is equal to or less than the pressure 25 percent below the vehicle manufacturer's recommended cold inflation pressure or the pressure specified in the 3rd column of Table 1 of this standard for the corresponding tire type, whichever is higher (

see

S4.2(a)).

A number of commenters raised concerns about the 25-percent under-inflation detection level proposed in the NPRM. Although their reasoning differed, these commenters all argued that a more stringent detection level should be required under the final rule.

Public Citizen stated that a 20-percent threshold should be adopted. Public Citizen argued that NHTSA's technology-neutral standard, as proposed, was crafted to accommodate indirect TPMSs (which Public Citizen considers to be an “inferior technology”) when there is other adequate technology readily available (

i.e.

, direct TPMSs). (Advocates for Highway and Auto Safety (Advocates) provided a similar comment.) According to Public Citizen, NHTSA should not reduce safety requirements in order to accommodate inferior technology, particularly when other affordable and more effective technology exists.

Public Citizen stated that the aspect of the agency's rationale that a higher threshold could discourage technological innovation is unsubstantiated. The comments of Public Citizen similarly characterized as unsubstantiated NHTSA's concerns about nuisance warnings that could result from a detection level that is set too close to placard pressure and requested substantive driver behavioral research to confirm that this would be a problem. (Similarly, Advocates argued that NHTSA acted arbitrarily in selecting a 25-percent under-inflation threshold (as opposed to the 20-percent level proposed in the 2001 NPRM) and that the record does not justify NHTSA's claim that a 20-percent under-inflation detection level would result in nuisance warnings.)

Public Citizen rounded out its comments in this area by characterizing the NPRM's 25-percent under-inflation detection level as a cost-saving measure. It argued that safety should outweigh cost considerations and that NHTSA's other rulemaking activities provided support for adopting a 20-percent under-inflation detection level (

e.g.

, the 2001 TPMS NPRM and the agency's rollover research). The Advocates argued that NHTSA has not compared the actual benefits of the two thresholds and suggested that NHTSA's New Car Assessment Program (NCAP) data would support the theory that different pressure levels correlate with different levels of risk.

Fairfax County Public Schools expressed support for a system that either provides a built-in tire pressure gauge or provides an earlier warning, such as a 20-percent under-inflation detection level. It stated that it is not always easy to find a functioning air compressor when traveling, so it is better to provide an earlier indication before the vehicle is past the point of safe operation.

Mr. James Anderson, an individual, commented that the under-inflation detection level should be set at some point between 15 percent and 18 percent below placard pressure, the point at which the commenter argued that the tire sidewall begins to over-flex. According to Mr. Anderson, as the tire over-flexes, heat begins to build up, but the tire is no longer able to dissipate the heat. Mr. Anderson stated that at some point above 200 °F, the tire compounds begin a reversion process, which may lead to delamination and, ultimately, separation of tire components. He argued that a warning level 25-percent below placard pressure would not permit sufficient time for driver recognition and timely action to correct the under-inflation situation before tire damage may occur.

The Tire Industry Association (TIA) argued that the proposed TPMS under-inflation detection level is too lenient, suggesting that the trigger point instead should be tied to the vehicle's placard pressure and GAWR. Specifically, TIA stated that the under-inflation detection warning should be triggered at 1-2 psi below the vehicle's recommended cold tire inflation pressure or at an inflation level where the tires can no longer carry the vehicle weight, whichever is higher. (TIA's argument here is related to the issue of Tire Reserve Load, a topic discussed later in this document.) TIA argued that the standard should require the TPMS to provide a warning before there is a serious problem, thereby taking into account that drivers may not immediately take corrective action when the warning telltale illuminates.

ETV Corporation (ETV) stated that the TPMS should be required to take into account different load conditions in determining the need to activate the low tire pressure warning.

The National Automobile Dealers Association (NADA) stated that although the final rule must factor in technological and cost constraints, it should specify the smallest under-inflation threshold that can be reliably monitored.

EnTire Solutions, LLC (EnTire) commented that the direct TPMSs it produces are capable of providing low pressure warnings at a more stringent threshold than the NPRM's proposed 25-percent under-inflation detection level. EnTire also stated that its system and those of other TPMS manufacturers have multiple thresholds for under-inflation detection. GE Infrastructure Sensing stated that technology currently exists for TPMSs to detect a 20-percent under-inflation level.

The Tire Rack argued that the 25-percent under-inflation detection level does not provide an adequate and timely warning to the driver and may provide a false sense of security. The Tire Rack also stated that, to the extent the 25-percent under-inflation detection level reflects limitations of current technology, the final rule should establish successively more stringent requirements in order to ensure future improvements in TPMS technology. It argued that establishing goals and timetables as part of the final rule would encourage technological developments for TPMSs.

The American Automobile Association (AAA) stated that the NPRM proposes to set the under-inflation warning threshold at a level that is insufficiently stringent, because a tire that is 25 percent below the manufacturer's recommended inflation pressure could already present a dangerous situation, particularly if the vehicle is in a fully-loaded condition. AAA argued that under-inflated tires “produce increased heat, which is a major cause of failure.” According to AAA, an effective TPMS is one that provides a warning before a dangerous situation is imminent and which does not mislead motorists into equating the absence of an illuminated warning light with safety.

BERU Corporation (BERU) commented that the under-inflation detection level should be set to trigger a warning at either 25-percent below placard pressure or a minimum activation pressure of 1.4 bar.

The Rubber Manufacturers Association (RMA) commented that lost fuel efficiency was not adequately accounted for in the assessment of economic costs when selecting an

under-inflation detection threshold. The RMA asserted that the NPRM's benefits calculations indicated that 26 percent of vehicles have tires that are under-inflated below placard pressure, but that associated fuel efficiency costs were not considered.

The Specialty Equipment Market Association (SEMA) argued that TPMSs should be reprogrammable in order to accommodate alternate and replacement tires with different pressure thresholds, or alternatively, the system could include “smart” software that would automatically detect the proper pressure threshold. According to SEMA, as currently proposed, when a higher-pressure tire is installed on the vehicle, the TPMS would not indicate low tire pressure until the tire is 25-percent below the value for the lower-pressure, original tire, and the converse would also be a problem, with the telltale actuating prematurely when a lower-pressure aftermarket tire is installed. SEMA stated that this situation would defeat the intent of the rule, give drivers a false sense of security, and be potentially problematic for new, low-profile tires that may be easily damaged.

As part of the final rule, we have decided to retain the proposed under-inflation detection level, by which the TPMS is required to illuminate a low tire pressure warning telltale whenever the inflation pressure in one or more of the vehicle's tires, up to a total of four tires, is equal to or less than their the pressure 25 percent below the vehicle manufacturer's recommended cold inflation pressure or the pressure specified in the 3rd column of Table 1 of this standard for the corresponding tire type, whichever is higher. We have reached this determination for the following reasons.

Selecting an appropriate notification threshold level for the TPMS is one of the most fundamental matters to be resolved as part of this rulemaking. It involves balancing the safety benefits of alerting consumers to low tire pressure against the risks of over-alerting them to the point where the warning becomes a nuisance that may be ignored. We believe that the final rule's 25-percent under-inflation detection level strikes the proper balance in this regard.

As discussed in the June 5, 2002 final rule, NHTSA conducted a tire pressure survey that inspected over 11,500 vehicles, which reported that 26 percent of passenger cars and 29 percent of light trucks had at least one tire that was 25 percent or more below the recommended inflation pressure for that vehicle (

see

67 FR 38704, 38713). However, despite this substantial percentage of vehicles with under-inflated tires at this level, incidents of tire failures remain infrequent. NHTSA conducted testing on a variety of Standard Load P-metric tires at 20 psi with 100-percent load at 75 mph for 90 minutes on a dynamometer, and none of these tires failed (

see

67 FR 38704, 38726 (June 5, 2002)). This testing led the agency to conclude that warnings at less severe conditions will give drivers sufficient time to check and re-inflate their vehicles' tires before the tires experience appreciable damage. Accordingly, we believe that an under-inflation detection level of 25 percent would have a strong fleet impact, holding driver behavior constant.

However, if we instead selected an under-inflation detection threshold that is too stringent, with some commenters arguing for a level as small as 1 or 2 psi below placard pressure, the warning telltale might illuminate frequently, and the driver would need to repeatedly stop and add a small amount of air to the tires in order to extinguish the telltale. After servicing the tires in this manner for the first few times, the driver might decide to postpone action on the TPMS's warnings or ignore such warnings entirely. Thus, if the under-inflation warning threshold were to be set too low, the safety benefits associated with the TPMS's low pressure warning could be lost. Because we have determined that a 25-percent under-inflation detection threshold already provides a warning to the driver before adverse safety consequences arise, providing a more stringent warning threshold would not be expected to provide additional safety benefits, although it could increase the risk of the nuisance warnings discussed above.

We disagree with Public Citizen's reading of the Court's decision in

Public Citizen

Mineta

, implying that the Court had somehow ruled against NHTSA's development of a technology-neutral standard or its consideration of costs as a part of the rulemaking. In fact, the Court held that it was appropriate for NHTSA to consider costs as part of the rulemaking, stating “the agency was correct to consider the relative costs,”

although the Court disagreed with how the agency weighed those costs in setting compliance options in the June 2002 final rule. Furthermore, the Court specifically found the four-tire, 25-percent under-inflation detection level to be reasonable. The Court held, “Given that the 25 percent standard was a substantially more cost effective means of preventing injuries and saving lives than the 20 percent standard, we conclude that it was reasonable for NHTSA to adopt the former and reject the latter.”

Public Citizen

Mineta

, 340 F.3d 39, 57 (2d Cir. 2003).

. at 62.

Available agency data show that a TPMS with a four-tire, 25-percent under-inflation threshold is more cost-effective than one with a four-tire, 20-percent under-inflation threshold. This issue was specifically addressed in the Final Economic Assessment (FEA) for the June 2002 final rule, which found that the net cost per equivalent life saved for a four-tire, 20-percent system would be $5.1-$5.3 million but that the net cost per equivalent life saved for a four-tire, 25-percent system would be $4.3 million.

Although we realize that the precise values of these figures are somewhat outdated, we believe that their cost-effectiveness relative to each other has not changed significantly. For additional information on the cost of alternative systems considered, please consult the FEA and the Final Regulatory Impact Analysis (FRIA) for this final rule, which has been included in the docket for this rulemaking.

See

page

of the FEA (Docket No. NHTSA-2000-8572-216).

We are not adopting BERU's recommendations regarding the under-inflation detection test procedures because BERU has not provided any rationale to explain why the existing procedures are inadequate.

Regarding the issue of TPMS reprogrammability raised by SEMA, we have decided to permit, but not require, such a feature. However, we reiterate that we will conduct compliance testing with the tires installed on the vehicle at the time of initial sale, and we will follow manufacturer instructions for resetting the TPMS.

(b)

Time Period for Low Pressure Detection

. As noted above, paragraph S4.2(a) of the NPRM proposed to require the TPMS to detect and provide a warning to the driver within 10 minutes after a tire becomes significantly under-inflated (

i.e.

, reaches the warning threshold specified in the standard). Under paragraph S4.2(b), the NPRM proposed to require the low pressure telltale to continue to illuminate as long as the pressure in any of the tires is equal to or less than the activation threshold specified in S4.2(a) and the ignition locking system is in the “On” (“Run”) position, whether or not the engine is running. The NPRM proposed that the telltale must extinguish after the inflation pressure is corrected.

A number of commenters urged NHTSA to modify this ten-minute detection time requirement as part of

the final rule, with some commenters recommending a longer time period and others recommending a shorter one.

Manufacturers that commented on low pressure detection time generally recommended extending the time period. BMW of North America, LLC (BMW) stated that the TPMS requirements should reflect real world needs. As a result, BMW stated that the NPRM's 10-minute detection requirement should be retained when only one tire becomes significantly under-inflated (

e.g.

, to detect situations where a tire is punctured by a nail or sustains other damage that could result in a relatively rapid loss of inflation pressure). BMW stated that when two, three, or all four tires become significantly under-inflated at the same time, the detection time requirement should be extended to 90 minutes, because under-inflation in these circumstances is likely to result from slow diffusion over months and is not likely to result in a problem requiring immediate attention. NIRA Dynamics provided similar arguments and reasoning, although it recommended a detection time of 20 minutes for a single tire and at least one hour for multiple tires.

Sumitomo Rubber Industries (Sumitomo) offered a different assessment of the time needed for low pressure detection. Sumitomo stated that it is appropriate to maintain a 10-minute detection (and extinguishment) requirement for one tire, but that a TPMS would need at least 30 minutes (preferably one hour) to detect (and extinguish) multiple under-inflated tires.

In its comments, Hyundai American Technical Center, Inc./ Kia Motors Corporation (Hyundai) provided yet another recommendation regarding low tire pressure detection time, stating that the time period for detection and verification of low tire pressure under the standard should be extended to at least 20 minutes. Hyundai stated that delivery frequency for data from the direct TPMS tire pressure sensor to the main control unit can take as long as three minutes, which is a function of Federal Communications Commission (FCC) requirements

that limit signal transmissions and the capacity of the battery in the sensor. In addition, Hyundai stated that a number of transmissions may be required to correctly diagnose low tire pressure. Therefore, if a wireless data error occurs, Hyundai argued that the TPMS may not be able to gather sufficient data within the NPRM's proposed 10-minute time limit to assess the vehicle's tire pressures. Accordingly, Hyundai argued that the final rule should permit at least 20 minutes for low tire pressure detection in order to give the TPMS sufficient time to gather enough data to make an accurate assessment.

See

47 CFR 15.231.

Volkswagen of America, Inc., Volkswagen AG, and Audi AG (VW/Audi) commented that in order to overcome the technology-limiting requirements of the NPRM, the final rule should permit a driving time of up to one hour for the low tire pressure warning, a time period consistent with detecting the unlikely situation where all four tires become under-inflated due to slow air leakage or changes in ambient temperature.

In contrast, other commenters argued that the NPRM's 10-minute under-inflation detection time is too long and should be reduced. Public Citizen argued that the requirement for under-inflation detection time should be reduced to one minute in the final rule, because direct TPMSs can meet such a requirement. Public Citizen stated that in proposing a 10-minute under-inflation detection requirement, NHTSA has unjustifiably lowered the bar in order to accommodate more manufacturers (

i.e.

, to permit indirect TPMSs requiring a longer time period for detection).

ETV commented that the TPMS should be required to activate (and extinguish) its warning within 10 seconds of vehicle start-up in order to prevent the vehicle from entering traffic with a potentially dangerous level of tire under-inflation.

The EC commented that the 10-minute detection time for the low tire pressure warning does not adequately address the tire safety problem, because during this period, the tire(s) may be operated at pressures even lower than 25-percent below the recommended pressure and significant structural damage could occur during that time period. The EC expressed concern that a combination of high speed, a long activation period, and a 25-percent under-inflation detection level could significantly reduce the time available to the driver to take appropriate action. (The European Tyre and Rim Technical Organisation (ETRTO) provided a similar comment.) The RMA similarly objected to the 10-minute activation time period as being unsafe; the RMA argued that, particularly at higher speeds, that activation time would allow the vehicle to travel with under-inflated tires for many miles with excessive heat, over-deflected body cords, and possible structural damage.

According to Emtop Ltd. (Emtop), the NPRM's 10-minute under-inflation detection requirement does not address the 15 percent of incidents of under-inflation caused by rapid pressure drop (Emtop's estimate). Emtop argued that the proposed requirement is dictated by the inability of many current systems to meet a more stringent requirement for detection time. Emtop stated that its TPMSs can detect rapid pressure losses “in a fraction of a second” and that the TPMS rule should not create barriers to such high-performance systems.

MLHO, Inc. (MLHO), which has developed a battery-less, non-radio-frequency (RF) TPMS that relies on directional magnetic coupling to send pressure information, commented that there is no need for a TPMS to provide either an under-inflation warning or a malfunction warning while the vehicle is stationary. (In simple terms, in the MLHO TPMS system, wheel rotation powers the transmitter.) The commenter argued that a very flat tire will be obvious to the driver or will trigger the warning before the vehicle has traveled a significant distance. As to the malfunction indication, MLHO argued that since a TPMS malfunction does not constitute an emergency, the malfunction need not to be detected prior to vehicle movement.

Instead, MLHO recommended that the proposed detection requirements in S4.2 of the NPRM should be revised to require the TPMS to detect the significantly under-inflated tire(s) and to illuminate the low tire pressure telltale within 10 minutes after the vehicle is in motion within the standard's designated speed range. MLHO requested that NHTSA also include language in S4.2 to specify that the TPMS will not be expected to either illuminate or extinguish the low tire pressure telltale without the vehicle being in motion, as motion is necessary for some systems to assess the vehicle's tire pressure status.

MLHO stated that as currently proposed, the NPRM imposes unnecessary design restrictions, favors the “present dominant RF-based technology,” and discriminates against small businesses.

NHTSA has carefully considered the commenters' countervailing arguments regarding the time limit for the TPMS to detect a significantly under-inflated tire, and we have decided to modify the relevant requirement in this final rule. As revised, under S4.2 of the standard, the TPMS must illuminate a low tire pressure warning telltale not more than 20 minutes after the inflation pressure in one or more of the vehicle's tires, up to a total of four tires, is equal to or less

than the pressure 25 percent below the vehicle manufacturer's recommended cold inflation pressure or the pressure specified in the 3rd column of Table 1 of this standard for the corresponding tire type, whichever is higher. We believe that this detection time period is appropriate for the following reasons.

As noted in the agency's June 5, 2002

Federal Register

notice, TPMSs were not developed to warn the driver of extremely rapid pressure losses that could accompany a vehicle encounter with a road hazard or a tire blowout.

According to the tire industry, those types of events account for approximately 15 percent of pressure loss cases.

Arguably, a driver would be well aware of the tire problem in those situations, and the TPMS would provide little added benefit. Instead, TPMSs' benefits lie in warning drivers when the pressure in the vehicle's tires is approaching a level at which permanent tire damage could be sustained as a result of heat buildup and tire failure is possible; this low level of inflation pressure generally results from a more measured pressure loss (produced over weeks or months) caused by a slow leak, defective valve, or diffusion. According to the tire industry, approximately 85 percent of all tire pressure losses are slow air losses that occur over hours, weeks, or months of vehicle use.

In those cases, a detection time of 20 minutes is not likely to pose a safety risk to the driving public.

67 FR 38704, 38728 (June 5, 2002).

Id.

The agency's tire research suggests that even in a 25-percent under-inflated condition, the vehicle can be operated safely for this detection period without an appreciable risk of tire failure. Specifically and as noted above, NHTSA conducted testing on a variety of Standard Load P-metric tires at 20 psi with 100-percent load at 75 mph for 90 minutes on a dynamometer, and none of these tires failed.

This testing led the agency to conclude that warnings at less severe conditions will give drivers sufficient time to check and re-inflate their vehicles' tires before the tires experience appreciable damage. Commenters advocating a reduced detection time did not provide any evidence to demonstrate that operation of the vehicle with one or more tires under-inflated by 25 percent leads to tire damage or tire failure. Although manufacturers are encouraged to provide the low tire pressure warning as quickly as possible, we believe that a 20-minute detection period is unlikely to result in any adverse safety consequences.

Id.

at 38726.

We further believe that a change in the detection time is necessary in order to articulate a standard that is practicable and technology-neutral. According to manufacturers' comments, even direct TPMSs will require additional time to detect and verify low tire pressure, in part as a result of FCC regulations limiting the frequency of electronic transmissions.

Furthermore, we anticipate that the extended time period also will ease compliance for indirect systems (particularly when detecting multiple under-inflated tires). Most indirect and hybrid TPMSs cannot currently meet the four-tire, 25-percent under-inflation detection threshold within 20 minutes. However, we are aware of at least one indirect TPMS that is currently capable of doing so,

and we expect that with additional time and effort, other indirect and hybrid systems also would be able to meet the requirements of the standard.

Docket No. NHTSA-2004-19054-96.

In sum, without an extension of the time period for low tire pressure detection and warning, the number of TPMS technologies available for use under the standard may be significantly curtailed. Available information does not demonstrate a safety need for imposing such limitations, and we believe that drivers would operate the vehicle for 20-minutes periods with some frequency. For these reasons, we believe that a 20-minute detection time period is both practicable and meets the need for motor vehicle safety.

We have decided not to extend the low tire pressure detection time beyond 20 minutes, however, as requested by some manufacturers in their comments. Available research shows that 75 percent of commuters regularly experience commute times of 30 minutes or less.

A recent study by the U.S. Census Bureau, using 2002 survey data, found that average commute times for most major U.S. cities range from 20 to 30 minutes.

Many other trips, such as routine errands, may also involve drive times of less than 30 minutes. Therefore, if we were to require a low tire pressure detection time of 30 minutes or more, it is conceivable that consumers could be driving on significantly under-inflated tires for a potentially extended period of time without receiving a warning from the TPMS.

This statistic is based upon the results of a Washington Post-ABC News-Time poll conducted by telephone from January 27-31, 2005 among 1,204 randomly selected adults nationwide. Results of this poll were reported in the

Washington Post

on February 13, 2005, at page A1.

See http://www.census.gov/acs/www/Products/Ranking/2002/R04T160.htm.

In addition, we are concerned that extending low pressure detection time period beyond 20 minutes could be problematic in other situations. For example, where a tire is punctured by a nail or is otherwise damaged and may experience a moderately rapid pressure loss. As to damaged tires but experiencing a relatively less rapid pressure loss, research into the rate of temperature buildup shows that for constant load, pressure, and speed conditions, tires generally warmed up and stabilized their temperatures within 15 minutes of testing;

thus, the tire will rapidly reach a temperature that places stress on an under-inflated tire. In both of those cases, we are concerned that a 30-minute detection time could delay the warning to the driver too long. For these reasons, we have decided that a requirement that would permit a low tire pressure detection time longer than 20 minutes could diminish the overall utility of the TPMS and concomitantly reduce the safety benefits associated with that system.

See

June 5, 2002 comments of the Rubber Manufacturers Association (Docket No. NHTSA-00-8011-64).

In response to the concerns of MLHO, it was never the agency's intention to require detection absent vehicle motion. As demonstrated by the standard's test procedures, the detection time for low tire pressure includes a period of vehicle operation within a designated speed range (

see

S6(f)). This provision for vehicular motion is already built in to the general requirements of S4.1, which provides that the TPMS must meet the detection requirements of S4 under the test conditions specified in S5 and the test procedures specified in S6 of the standard. We believe that no further modifications to the standard are necessary related to this point.

2. TPMS Malfunction Indicator Lamp (MIL) Activation Requirements

Paragraph S4.4 of the NPRM proposed to require each covered vehicle to be equipped with a TPMS that includes a telltale that illuminates whenever there is a malfunction that affects the generation or transmission of control or response signals in the TPMS and extinguishes when the malfunction has been corrected.

The NPRM's proposed requirement for a TPMS Malfunction Indicator Lamp (MIL) was not included in earlier rounds of the TPMS rulemaking process. Consequently, the agency

expected and did receive extensive public comment on this proposed provision. Commenters offered recommendations regarding how quickly the TPMS must detect system malfunctions, the types of functions to be detected, and the test procedures for detecting such malfunctions. Each of these topics will be discussed in turn.

(a)

Time Period for Malfunction Detection.

The NPRM did not specify a time period for the TPMS to detect a malfunction and to illuminate the TPMS MIL.

The Association of International Automobile Manufacturers, Inc. (AIAM) expressed concern that the NPRM would require detection and notification of a TPMS malfunction immediately upon occurrence. However, AIAM stated that immediate detection is not possible in most cases, because TPMSs generally require the vehicle to be in motion in order to detect a malfunction (an argument also raised by Honda Motor Co., Ltd. and American Honda Motor Co., Inc. (Honda) and EnTire), and several transmissions from the pressure sensor to the controller are required to validate the existence of a malfunction.

AIMA stated that the FCC requires a pause between signal transmissions at least 30 times as long as the signal transmission itself. In addition, AIMA stated that interference may result in the loss of some of these signals. AIMA argued that a requirement for immediate detection and reporting of a TPMS malfunction could result in many false positive warnings, which could undermine consumers' faith in the system and potentially lead them to ignore TPMS-related warnings (an argument repeated by General Motors North America (GM) and Hyundai in their comments). In light of the above, AIMA recommended that the agency allow the TPMS between 30 and 60 minutes to determine with a high degree of certainty whether a true malfunction is present (

e.g.

, not one caused by signals external to the vehicle). The Alliance made a similar comment, suggesting a 30-minute detection time for a malfunction.

Several other commenters also recommended that the agency specify a time period for the detection of a TPMS malfunction, although the recommended time periods varied. For example, ALPS Automotive, Inc. (ALPS) and Honda commented that a TPMS cannot detect malfunctions any faster than the system can detect low tire pressure and that the same durational parameters should be set for both functions. ALPS, BERU, Schrader Electronics, Ltd. (Schrader), and Fuji Heavy Industries USA, Inc. (Fuji) each recommended a 10-minute detection time. BERU stated that it does not support an “excessive[ly] long” duration for TPMS malfunction detection, because an extended ride (even 20 minutes) with a defective TPMS or an incompatible tire could prevent a low pressure warning and lead to a tire blow out. BERU also recommended specification of a vehicle moving distance. BERU stated that specifications for “duration” and “vehicle moving distance” are necessary not only for the detection of a malfunction, but also for the validation of the correction of a malfunction.

EnTire and Hyundai recommended a malfunction detection time of 20 minutes. According to EnTire, if a pressure sensor is disabled, it can take over 13.5 minutes for the fault to “mature” and to be detected by the system and suggested 20 minutes as a reasonable detection time. (EnTire also suggested 20 minutes as a reasonable extinguishment time for the MIL, and Fuji recommended that a vehicle be driven at least 10 minutes at a minimum of 40 kph in order to verify that the malfunction has been eliminated.) Hyundai commented that current direct TPMSs are designed so that a failure is recognized only when the control unit does not receive data from the pressure sensor for three to four consecutive delivery cycles. Hyundai stated that current systems, therefore, require approximately 20 minutes to properly detect and verify TPMS malfunctions, a time period consistent with minimization of nuisance warnings.

GM recommended a 30-minute drive time for TPMS malfunction detection. GM stated that the MILs for its current TPMSs have a 25-minute drive period for the detection threshold, and the company is not aware of any consumer complaints arising from delayed TPMS malfunction warnings. GM argued that a TPMS that is programmed to be highly reactive in terms of malfunction detection and that provides an immediate response may result in relatively frequent malfunction warnings because common, everyday occurrences are likely to temporarily disturb the TPMS's signals.

MLHO stated that the regulatory text related to the TPMS malfunction detection requirement should be revised to focus on the detection of a malfunction or correction of a malfunction, rather than the occurrence of those events. MLHO's comment is related to those about the need for the system to have adequate time to detection the presence or absence of a malfunction.

DaimlerChrysler Corporation (DaimlerChrysler) made a general argument that NHTSA has not calculated or otherwise demonstrated any significant safety benefits associated with the TPMS MIL.

Based upon the information provided by the commenters, we have decided to modify our approach to the MIL by providing a time period for malfunction detection and a speed range in which the vehicle will be driven as part of the malfunction detection phase in the test procedures. Specifically, this final rule requires the TPMS to detect a malfunction and to illuminate the MIL within 20 minutes of the occurrence of a malfunction, when the vehicle is driven at a speed between 50 km/h and 100 km/hr.

Several commenters have stated that TPMSs generally require the same amount of time to detect and to verify a malfunction as they do for low tire pressure. As discussed above, the detection time period for low tire pressure has been increased to 20 minutes. A number of commenters stated that 20 minutes would provide adequate time for TPMS malfunction detection, with some commenters recommending an even shorter time period (

e.g.

, 10 minutes). We also believe that specifying a time period for detection addresses MLHO's comment that the standard should not imply a requirement for automatic illumination of the MIL as soon as a malfunction occurs.

We understand that certain TPMS technologies require vehicular motion in order to diagnose a TPMS malfunction, which is similar to the way in which such systems detect low tire pressure. For that reason, we are now specifying in the standard's test procedures that the vehicle will be driving within a designated speed range during the malfunction detection phase.

We see important benefits in including a MIL requirement as part of the final rule. First, the malfunction detection requirement is intended to ensure the long-term functionality of the TPMS by identifying those small number of replacement tires with construction characteristics that would prevent proper operation of the TPMS. Without the TPMS MIL, some drivers would lose the benefit of the low tire pressure warning to be provided by the TPMS. The malfunction indicator was recommended by the Alliance as a solution to this problem. In addition, the MIL could provide ancillary benefits by alerting the driver of other situations where the system becomes non-operational; in some cases, the problem may be temporary (

e.g.

, brief signal

disturbance), but in other cases, the MIL may signal the need for repair of the TPMS. In all these cases, it is useful to the driver to be aware that the system is unavailable to provide a low tire pressure warning.

However, with the above said, we do believe that the above accommodations can be made without any significant decrease in safety benefits. A TPMS malfunction does not itself represent a safety risk to vehicle occupants, and we expect that the chances of having a TPMS malfunction and a significantly under-inflated tire at the same time are unlikely. Even if that is the case, we do not believe that a 20-minute detection time would increase occupant risk appreciably.

(b)

What Constitutes a TPMS Malfunction?

The NPRM proposed to require the MIL to illuminate “whenever there is a malfunction that affects the generation or transmission of control or response signals in the vehicle's tire pressure monitoring system” and to extinguish when such malfunction is corrected (S4.4(a)).

A number of commenters argued that proposed malfunction requirement is overly broad and in need of modification. The Alliance, the organization that originally suggested consideration of a TPMS MIL, stated that it remains committed to providing an in-vehicle indication when there is inadequate signal reception from one or more TPMS sensors. However, the Alliance stated that the technical specifications for the MIL proposed in the NPRM are different than the MILs that Alliance members were expecting and, in some cases, are inconsistent with the MILs that manufacturers are already voluntarily providing.

Fuji stated that although it is reasonable to require malfunction detection for components that sense and transmit tire inflation pressure data, the standard should only require malfunction detection and warning in three situations: (1) When there is inadequate (or no) input signal from the wheel sensors; (2) when there is inadequate (or no) input signal from the antenna to the electronic control module (ECM), or (3) when there is inadequate (or no) input signal from other systems used by the malfunction warning system (

e.g.,

ABS wheel speed input to the ECM). Fuji stated that malfunctions in the TPMS ECM (which contains the logic to determine that a malfunction exists) would be impossible to indicate via the MIL, because the module would not be functioning to operate the lamp.

Sumitomo commented that paragraph S4.4, as proposed, should be modified to require the TPMS to indicate a malfunction under the following two conditions: (1) When wheel speed signals cannot be transmitted from wheel speed sensors to the TPMS, and (2) when tire pressure signals cannot be transmitted from the pressure sensors to the TPMS.

ETV stated that the MIL should indicate the following malfunctions: (1) Incompatibility of replacement tires/rims; (2) sensor failure; (3) signal failure in communications channel; (4) reader electronics failure, and (5) telltale bulb failure. ETV argued that there should be a redundancy or failsafe built into the system so that a burnt out telltale bulb can still produce a malfunction warning, so as to alert the consumer that that bulb needs replacement.

Hyundai stated that there are three types of TPMS malfunctions that will require addition of a separate electrical circuit to activate the MIL: (1) Disconnection of the power source to the main control unit; (2) disconnection of the power source to the telltale lamp, and (3) disconnection of wiring between the main control unit and the telltale lamp. Hyundai requested that the agency exclude these three malfunctions from the requirements of the standard during the phase-in period, because incorporating detection capabilities for these types of malfunctions would require additional development time. Alternatively, Hyundai suggested that detection of these conditions could be achieved through the bulb check function and supplemental language in the owner's manual; in those cases, the TPMS lamp would not be illuminated during the bulb check, and the driver would consult the owner's manual to be alerted to the TPMS malfunction in such cases.

In addition, Hyundai stated that even though components such as the electronic control unit (ECU) or vehicle speed sensors are involved in TPMS operation, failure of these components should not be considered a TPMS malfunction. Mitsubishi stated that the MIL should not be required to provide a warning during brief interruption of communication between sensors and the ECU because the TPMS uses radio communications that can be affected by external interference; this is a common occurrence that could result in false positive warnings. GM made a similar point about not requiring the TPMS MIL to illuminate during brief and temporary interruption of signals.

The comments of American Suzuki Motor Corporation (Suzuki) discussed the malfunction detection capabilities of the TPMS currently installed on the Suzuki XL-7. According to Suzuki, that system provides a malfunction indication when there is either a loss of power to the TPMS control unit or when there is no electrical connection between the control unit and the TPMS telltale. Suzuki stated that although its system is not compliant with the NPRM's proposed MIL requirements, it believes that its system is just as effective as the MIL technical specifications in the NPRM. Therefore, Suzuki requested that NHTSA adopt “less design-restrictive” requirements for the TPMS MIL, so as to allow continued use of its system.

NIRA Dynamics commented that it is important to keep the malfunction indicator requirements generic, so that any TPMS technology may be used. As examples of limitations specific to certain types of TPMS technology, NIRA Dynamics stated that: (1) Many direct systems cannot detect a malfunction when the vehicle is stationary if the sensor does not have any contact with the receiver due to wheel angle; (2) it is impossible for indirect systems to detect a malfunction when the vehicle is stationary because the wheel must rotate to diagnose the sensor, and (3) indirect systems cannot detect tire incompatibilities. NIRA Dynamics urged that the final rule should simply require TPMSs to be designed to detect malfunctions “according to good engineering practices.”

Honda's comments sought confirmation that the following system failures would be excluded from the TPMS MIL activation and warning requirements: TPMS indicator light, TPMS coupler, and meter panel. Honda argued that it would be unnecessary for the TPMS MIL to report these failures because they would be apparent upon bulb check. Honda also requested that the agency issue a laboratory test procedure for generating a TPMS system fault, so as to clear up any confusion related to the types of malfunctions that will be subject to testing.

Continental Teves, Inc. (Continental Teves) also commented that for a hybrid system, it would not be possible for the TPMS to illuminate the MIL to indicate an incompatible tire unless it is on a wheel with a pressure sensor. Continental Teves stated that the TPMS MIL should not be required to illuminate when an incompatible replacement tire is installed, but instead, the system should be permitted to continue to function with reduced performance without the MIL being lit. BMW also stated that the TPMS MIL should not be required to illuminate when system failure is the result of a change to an incompatible tire, because

such failure is not the result of a malfunction of the TPMS.

Schrader commented that the TPMS should not be required to signal a malfunction when the ignition locking system is in the lamp-check position, because that status check should be reserved for confirming the functionality of the telltale bulb.

After careful consideration of the public comments, we have decided to retain the NPRM's requirement for the MIL to illuminate whenever there is a malfunction that affects the generation or transmission of control or response signals in the vehicle's tire pressure monitoring system. Although the commenters expressed preferences for TPMSs with reduced malfunction detection capabilities, they did not state that it would be impracticable to provide the proposed warnings. Furthermore, we believe that, given adequate lead time, this requirement is practicable, because a nearly identical malfunction requirement for anti-lock braking systems (ABS) is contained in FMVSS No. 121,

Air Brake Systems,

and vehicle manufacturers have certified to that standard successfully. We expect that manufacturers would similarly be able to meet the malfunction detection requirements of the TPMS standard.

As drafted, the TPMS malfunction detection requirement is technology-neutral and capable of accommodating system design changes without the need to continually amend the standard. For example, in a direct TPMS, the control signals are generated by the wheel sensor and transmitted to an electronic control unit via an antenna. In contrast, in an indirect TPMS, the control signals may be generated by the ABS wheel sensor and transmitted to the electronic control unit directly. The present requirement encompasses both types of systems.

In response to comments suggesting that the TPMS MIL should only detect specific malfunctions, the agency believes that such restrictions would unnecessarily reduce the safety benefits of the TPMS. Specifications in the standard that would limit malfunctions that must be detected could impose design restrictions on manufacturers because such specifications and the components to which they refer may not be applicable to current or future TPMS designs. The agency recognizes that the requirement for malfunction detection includes all TPMS components and may require some additional circuitry and software, but we believe that with minor modifications, it would be practicable to monitor all TPMS components for malfunction. Therefore, we are not adopting the specific limitations recommended by the commenters.

We agree with the comment of Schrader that the MIL should not be required to signal a burned out bulb as a TPMS malfunction, because that problem would already be identified during the check-of-lamp function at vehicle start-up.

As discussed previously, we recognize that most TPMSs require vehicular motion in order to detect a system malfunction, so we have incorporated a 20-minute drive time in a designated speed range as part of the standard's test procedures for malfunction detection.

We do not agree with the comments stating that the MIL should not be required to illuminate during periods of brief external signal disturbance. The TPMS is unlikely to know for how long a signal disturbance will continue. Instead, we believe that the driver should be provided a warning that the TPMS system is unavailable to detect low tire pressure. This situation is not a false positive, but instead, it involves a period when the TPMS is unavailable, although through no fault of its own. Once the period of signal disturbance passes, the TPMS should detect that the problem has been resolved and extinguish the MIL, and no additional action on the part of the driver would be required.

In addition, during periods of brief disturbance, the TPMS's circuitry and software may require time to detect a malfunction, and the MIL telltale may ultimately not illuminate. As discussed above, we are requiring the TPMS to detect a malfunction and to illuminate the TPMS MIL within 20 minutes of the occurrence of such malfunction. This time period for detection should provide the system with an adequate opportunity to determine whether the disturbance is, in fact, brief before illuminating the MIL.

We also disagree with commenters who suggested that the TPMS MIL should not be required to signal when the vehicle is equipped with alternate or replacement tires that prevent continued proper functioning of the TPMS. That requirement is key to the long-term functionality of the TPMS, and unless such a warning is provided, some drivers may lose the benefits of the system entirely. It is plainly foreseeable that most vehicles will outlast their original set of tires, so this requirement is necessary to ensure that consumers continue to receive the TPMS's important information related to low tire pressure.

In response to Honda's comment that the agency should rapidly issue a laboratory test procedure for generating a TPMS system malfunction, we would offer the following clarification and cautionary note. It is our intention to publish guidelines to test facilities that the agency contracts with to conduct compliance testing in the near future. These guidelines are referred to as compliance test procedures, and they are intended to provide a standardized testing and data recording format among the various contractors that perform testing on behalf of the agency, so that the test results will reflect performance characteristics of the product being tested, not differences between the various testing facilities. However, we would stress that vehicle manufacturers' certification responsibilities are linked to the requirements, test procedures, and test conditions articulated in the standard, not the laboratory test procedures.

(c)

MIL Disablement.

The NPRM did not contain any provision for MIL disablement.

Honda requested clarification as to whether it would be permissible to disable or to suppress the MIL when the TPMS sending units have been removed as a result of the replacement of the original equipment tires and rims with aftermarket components that are not compatible with the direct-sensing TPMS. Honda stated that it had previously received complaints from customers and dealers who encountered this situation and were confronted with a recurrent malfunction warning. The company expressed concern that if the MIL cannot be suppressed in these situations, consumers may become desensitized to MILs generally, which could have negative implications for occupant safety. NADA provided a similar comment.

We do not believe it is appropriate to permit disablement of the MIL when aftermarket tires and rims are installed on the vehicle that are not compatible with the continued proper functioning of the TPMS. In such cases, the TPMS MIL is performing its intended function. We believe that the MIL should continue to operate when tires and rims that are incompatible with the TPMS are mounted on the vehicle, not only to discourage such actions, but also to provide an ongoing reminder that the TPMS is unavailable to provide low tire pressure warnings.

3. Telltale Requirements

The NPRM proposed to require installation of either a single TPMS telltale (i.e., a combination telltale indicating both low tire pressure and system malfunction) or separate telltales

for low tire pressure and malfunction indication.

For the low tire pressure warning, paragraph S4.3 of the NPRM proposed to require a telltale that is mounted inside the occupant compartment in front of and in clear view of the driver, which is identified by one of the symbols for “Low Tire Pressure Telltale” in Table 2 of FMVSS No. 101,

Controls and Displays,

and is illuminated under the conditions specified in S4.2. For low tire pressure telltales that identify which tire(s) is (are) under-inflated, the NPRM proposed to require that each tire in that symbol must illuminate when the tire it represents is under-inflated to the extent specified in S4.2. That paragraph also proposed to require the low tire pressure telltale to illuminate during a check-of-lamp function, and stated that the telltale would not be required to illuminate when a starter interlock is in operation.

For the TPMS MIL, paragraph S4.4 of the NPRM proposed two options for compliance. As the first option, under S4.4(b), a vehicle manufacturer could install a dedicated TPMS malfunction telltale that is mounted inside the occupant compartment in front of and in clear view of the driver, which is identified by one of the symbols for “TPMS Malfunction Telltale” in Table 2 of FMVSS No. 101, and is continuously illuminated under the conditions specified in S4.4(a). That paragraph also proposed to require the MIL to illuminate during a check-of-lamp function, and stated that the telltale would not be required to illuminate when a starter interlock is in operation.

As the second option, under S4.4(c), a vehicle manufacturer could install a combined Low Tire Pressure/TPMS Malfunction telltale that continues to meet the low tire pressure detection requirements of S4.2 and S4.3 and meets the MIL requirements of S4.4(a) in the following fashion. The NPRM proposed to require the combined telltale to flash for one minute upon detection of any malfunction condition specified in S4.4(a) after the ignition locking system is turned to the “On” (“Run”) position. After the first minute, the telltale would be required to remain continuously illuminated as long as the malfunction exists and the ignition locking system is in the “On” (“Run”) position. The NPRM proposed that this flashing and illumination sequence would be required to be repeated upon subsequent vehicle start-ups until the situation causing the malfunction has been corrected, after which time the telltale must extinguish.

(a)

Function and Format of the Combined Low Pressure Warning/Malfunction Indicator Lamp.

A number of commenters discussed the issue of how the MIL would operate, particularly when it is combined with the low pressure warning telltale. No consensus was evident, as reflected by the variety of viewpoints in the following discussion of comments.

Some commenters argued that the proposed requirements for the TPMS MIL are design-restrictive and may impose unnecessary costs. In its comments, AIAM opposed the use of a flashing low pressure telltale to indicate TPMS malfunction when the MIL is part of a combined format, because such a format may require significant software and hardware changes. AIAM stated that a separate MIL will not be feasible for many vehicles, and that the NPRM's limited MIL design options would restrict a number of potentially innovative solutions (

e.g.

, voice malfunction indicators, other visual or text messaging displays).

AIAM argued that NHTSA instead should include a technology-neutral requirement for a MIL, but leave MIL design to the discretion of the vehicle manufacturer. Porsche Cars North America, Inc. (Porsche) argued that there is no evidence that clear and concise text messages create confusion, and the company recommended that the final rule permit text messages related to TPMS malfunction and permit those messages to be cleared by the driver (but not permit clearing of the low pressure telltale). The Alliance, BMW, DaimlerChrysler, and VW/Audi all expressed similar views regarding allowing design freedom for MILs with a mix of product offerings. Suzuki suggested that manufacturers should be permitted to explain how different malfunctions are identified in the vehicle owner's manual.

DaimlerChrysler stated that its experience has shown TPMS malfunctions to be uncommon events, and therefore, detailed MIL specifications are not warranted because they do not address a significant safety problem or provide a significant safety benefit. DaimlerChrysler argued that it should be sufficient to have the final rule that the malfunction indicator “be present, visible to the driver, perceptually upright, and explained in the owner's manual.”

Others were concerned that the flashing-to-steady-burning MIL could lead to consumer confusion. The Alliance questioned whether having the combined telltale flash for one minute and then become steady burning to indicate a malfunction would confuse consumers as to whether a malfunction or a low tire pressure condition exists. More specifically, Hyundai stated that the initial one-minute flashing sequence may be an insufficient period of time, because, particularly at vehicle start-up, the driver may be preoccupied with other tasks and may not notice the flashing telltale until it becomes steady-burning, at which time it may be misconstrued to be a low pressure warning (a similar comment was provided by Emtop). Hyundai recommended that NHTSA either consider other alternatives (

e.g.

, periodic flashing) or an extension of the one-minute time period for the initial flashing. The comments of Mitsubishi Motors R&D of America, Inc. (Mitsubishi) and the TIA shared this view. DaimlerChrysler, Mitsubishi, and Nissan North America, Inc. (Nissan) went even further in their comments and suggested a continuously flashing TPMS MIL, which would be distinct from the continuous warning for low tire pressure.

TIA also expressed concern that even if the driver does notice the initial flashing sequence of the combined TPMS telltale, that person still may not comprehend its significance, instead misconstruing it as part of normal vehicle start-up. According to TIA, if that were the case, even a more detailed explanation in the owner's manual would be insufficient because the driver may never realize the need to consult it. TIA also commented that a separate TPMS MIL telltale would add yet another light to an already crowded dashboard. (BMW and Porsche provided similar comments.) BMW commented that a combined telltale would preserve space for future safety-related technologies and warnings.

Porsche argued that the 60-second flashing format for the proposed combined telltale is unwarranted and a potentially dangerous way to signal a TPMS malfunction. According to Porsche, a flashing telltale would send an incorrect message to the driver that something is seriously wrong with the vehicle, potentially alarming the driver and leading to a panic situation that could distract the driver's attention from driving.

In contrast, Emtop argued that there is not any evidence to suggest that flashing telltales produce inappropriate driver responses or that the intended messages are misunderstood, unless the indication is inconsistent.

Fuji's comments suggested that the form of the MIL warning should depend upon the type of malfunction encountered. More specifically, Fuji stated that malfunctions in the TPMS

ECM (which contains the logic to determine that a malfunction exists) would be impossible to indicate via the MIL, because the module would not be functioning to operate the lamp. Fuji recommended that the MIL should flash as long as the malfunction exists in components “downstream” of the ECM (

e.g.

, loss of signal from a wheel sensor) but that the MIL should have continuous illumination for malfunctions of components “upstream” of the ECM (

e.g.

, wiring harness to telltale, loss of power to the ECM). Fuji stated that this hierarchy would not apply to situations where the TPMS failed the bulb check.

NADA stated that the TPMS could use a single warning lamp to indicate a variety of conditions (

i.e.

, low tire pressure, incompatible tires, TPMS malfunction). Under the approach recommended by NADA, when the telltale is illuminated, the owner would consult (at least the first time) the following decision tree provided in the vehicle owner's manual in order to determine the meaning of that illumination: (1) There is an inflation concern. Check tire pressures. If okay, proceed to (2); (2) A tire is incapable of being monitored. Check tires. If okay, proceed to (3); (3) The system is faulty. See your motor vehicle dealer. NADA stated that the final rule should include a requirement for owner's manual language consistent with its recommended approach.

Emtop commented that having separate TPMS telltales for low tire pressure and the malfunction indicator is inadvisable because an additional telltale is costly, would consume limited display space, and would provide little or no additional safety benefit. In contrast to earlier commenters, Emtop argued that having separate telltales would confuse drivers and undermine confidence in the TPMS, and it also argued that allowing a choice in format could further confuse consumers who drive multiple vehicles when they encounter systems with different indicators.

In addition, Emtop recommended reversing the NPRM's approach to the low pressure and MIL warning signals, urging the agency to require the telltale to flash to indicate low tire pressure and to be continuously illuminated to indicate a TPMS malfunction. According to Emtop, a flashing telltale is more likely to be noticed and implies a potential danger, so in this case, Emtop recommended requiring the telltale to flash continuously to indicate low tire pressure, a potentially serious condition which is relatively easy for the driver to correct. (Honda provided a similar comment.) Emtop also recommended this approach because a flashing malfunction indicator would require a control signal that may be unable to produce the requisite flashing if the malfunction affects the control signal itself; according to Emtop, indicating a malfunction in a steady state would be more appropriate because an indicator can be made to default to a fixed state in the absence of a control signal.

In its comments, Emtop also questioned the message conveyed by a flashing-to-steady MIL, which it argued may be confusing, counter-intuitive, and context dependent. According to Emtop, drivers may equate a change in the indicator with a change in condition. Emtop also suggested that the messages in a combined telltale could be confused in situations where low tire pressure is masked by the malfunction warning or where a low pressure warning flickers (

e.g.

, due to fluctuating pressure causing the light to turn on and off), problems which may increase as future TPMS technology reduces system reaction time.

Emtop recommended specifying a flash rate of one to three times per second, noting that the flash rate could be changed to convey a greater sense of urgency to the driver if the situation deteriorates without being remedied. Emtop stated that its TPMSs already have a progressive flash rate that has been tested and well received by consumers. (EnTire and Honda also recommended specification of a flash rate for the 60-second flashing malfunction indication, as well as a tolerance for the 60-second period. EnTire recommended a tolerance for the 60-second period of ± 10 seconds, whereas Honda recommended a tolerance of ± 5 seconds.)

Public Citizen urged the agency to mandate separate warning indicators for low tire pressure and TPMS malfunction because a combined telltale could be confusing, particularly for older drivers who may have poorer vision and slower reaction times. (Advocates provided a similar comment.) Public Citizen argued that both warning telltales should be required to flash until the underlying problem is corrected. The organization stated that flashing telltales convey a sense of urgency and are more likely to elicit a driver response, and it suggested that a flashing indicator could be programmed to provide additional information, such as by flashing more frequently at increasingly lower pressure levels. Public Citizen argued that the agency has provided no support for a determination that flashing telltales are a nuisance or otherwise unacceptable.

BERU requested clarification of whether the MIL should be illuminated while the system is running validation protocols to determine whether a problem has been corrected. (Presumably, this question applies to both combined and separate TPMS MILs.)

EnTire sought clarification as to whether vehicles that are equipped with both of the proposed low tire pressure telltales (

i.e.

, the single symbol and the symbol showing individual tires) are required to have both symbols indicate a TPMS malfunction per the defined procedure or whether the MIL may be incorporated in only one of those telltales.

After considering the public comments and all available information, we have decided to retain the NPRM's general approach to the telltale requirements for both the low tire pressure warning and the TPMS malfunction indicator (with minor modifications), because we believe that this approach provides an effective message to virtually all drivers. As part of this final rule, we have decided to permit use of either separate telltales for the low tire pressure warning and the TPMS malfunction indicator, or a combined telltale that incorporates both functions. We believe that a visual telltale is necessary to provide a clear and consistent message to the driver. We do not believe that other suggested alternatives (

e.g.

, audible or text messages) would be as effective in providing those warnings. Furthermore, we are concerned that leaving the MIL to manufacturer discretion could result in a proliferation of warnings that may not be sufficiently noticeable or understandable to drivers. We believe that these warnings are extremely important in terms of providing tire pressure information to drivers or of alerting drivers when the systems is not available to provide such information. However, manufacturers may supplement the required warnings with these additional messages.

The agency's cost-benefit analysis does not support a mandatory requirement for separate telltales, and we acknowledge that with limited space available on the dashboard, a combined telltale has the potential to preserve precious space for future safety warnings. However, we believe that there is sufficient justification for separate warnings to warrant permitting manufacturers to use separate warning telltales if they elect to do so. We believe that providing these two different compliance options offers

manufacturers greater flexibility in terms of their designs without sacrificing the important safety messages related to the TPMS.

If the manufacturer chooses the option for separate telltales, the final rule requires a low tire pressure telltale that is mounted inside the occupant compartment in front of and in clear view of the driver, which is identified by one of the symbols for “Low Tire Pressure Telltale” in Table 2 of FMVSS No. 101, and is illuminated under the conditions specified in S4.2. For low tire pressure telltales that identify which tire(s) is (are) under-inflated, the final rule requires that each tire in that symbol must illuminate when the tire it represents is under-inflated to the extent specified in S4.2. That paragraph also requires the low tire pressure telltale to illuminate during a check-of-lamp function, and states that the telltale is not required to illuminate when a starter interlock is in operation.

For the dedicated MIL, under S4.4(b), the final rule requires the vehicle manufacturer to install a TPMS malfunction telltale that is mounted inside the occupant compartment in front of and in clear view of the driver, which is identified by the word “TPMS,” as described under TPMS Malfunction Telltale” in Table 2 of FMVSS No. 101, and is continuously illuminated under the conditions specified in S4.4(a). That paragraph also requires the MIL to illuminate during a check-of-lamp function, and states that the telltale is not required to illuminate when a starter interlock is in operation.

For the combined low tire pressure warning/MIL option, the final rule requires that the telltale must meet the low tire pressure detection requirements of S4.2 and S4.3 and also meet the MIL requirements of S4.4(a) in the following fashion. Upon detection of any condition specified in S4.4(a) after the ignition locking system is turned to the “On” (“Run”) position, the combined telltale must flash for a period of 60-90 seconds, after which, the telltale is required to remain continuously illuminated as long as the malfunction exists and the ignition locking system is in the “On” (“Run”) position. This flashing and illumination sequence must be repeated upon subsequent vehicle start-ups until the situation causing the malfunction has been corrected, after which time the telltale must extinguish.

The final rule's requirement for a 60-90 second time period of flashing of the combined telltale to indicate a TPMS malfunction represents an increase from the NPRM's proposed requirement. We agree with comments that drivers may be distracted by other tasks at vehicle start-up and in some cases may miss a 60-second flashing sequence.

However, we remain concerned that drivers may consider a lengthy or indefinite flashing sequence to be a nuisance, which could cause the driver to ignore the safety message. We are also concerned that the flashing telltale should elicit the appropriate driver response. Thus, the final rule's time period for flashing the combined telltale represents the agency's determination as how to best balance these competing concerns. We do not believe that it is necessary to specify a flash rate for the combined telltale, so we leave this matter to the discretion of the vehicle manufacturer.

Although certain commenters objected to the manner in which the low tire pressure and MIL warnings are to be provided, those commenters did not provide any evidence to show that the agency's approach would confuse consumers or that their suggested alternatives would be more effective. The following explains our reasoning in not adopting these suggestions.

We note, however, that in those cases where the driver does not see the flashing sequence, the anticipated response would be to check and inflate the vehicle's tires. Even if none of the vehicle's tires is “significantly under-inflated,” the outcome would be to return the tires to optimal pressure. This outcome would nevertheless be beneficial, although the driver may experience some consternation at the continued illlumination of the telltale. In addition, we do not expect that the driver would miss the MIL's flashing sequence on a regular basis.

The TPMS standard represents a novel case in terms of the agency's use of a telltale. Prior to this final rule, NHTSA has not required a flashing telltale for any of the safety systems in any FMVSS. Although we agree with commenters that a flashing telltale is likely to attract driver attention more quickly than a continuously illuminated telltale, we also must consider the appropriateness of the driver's response to the warning.

As we have discussed at various points in the course of this rulemaking, we do not believe that the TPMS's illumination of the low tire pressure telltale represents an urgent situation requiring immediate correction. As noted above, the agency's tire testing has shown that the vehicle can be operated safely with a tire that is under-inflated by 25 percent without an appreciable risk of tire failure for some reasonable period of time (

i.e.

, at least 90 minutes). If a significantly under-inflated tire does not constitute an urgent situation, a TPMS malfunction is even less likely to represent an emergency situation requiring immediate driver attention. Thus, in the situations that would generate a TPMS-related warning, the desired response would not be to have the driver immediately pull over to the side of busy highway. That is the primary reason why the color yellow was selected for the TPMS telltale(s), rather than red. It is also the reason why we have chosen to require continuous illumination of the dedicated TPMS MIL and to require a limited period of flashing followed by continuous illumination (rather than continuous flashing) of the combined TPMS telltale. Particularly when combined with the color yellow, we do not see any reason to believe that a flashing TPMS MIL telltale, in and of itself, would produce a panic response on the part of the driver. Furthermore, we do not believe it is necessary to require the combined telltale to produce periodic flashing more frequent than upon subsequent vehicle start-ups.

Some commenters suggested reversing the way the warning messages are presented in a combined telltale (

i.e.,

requiring flashing to indicate low tire pressure and continuous illumination to indicate TPMS malfunction). While these arguments are not illogical, we have decided that it is appropriate, in this regard, to retain the approach proposed in the NPRM. We believe that drivers are likely to encounter the low tire pressure warning much more frequently than the malfunction warning. Thus, we believe that this situation should be assigned the continuous illumination format, which represents the norm. The presumably less frequent TPMS malfunction warning is being assigned the flashing-to-continuous illumination format. Although it is arguably true that the low pressure situation would be easier for the driver to correct, we believe that the final rule's approach would minimize the amount of flashing encountered by the driver overall.

We believe that the messages presented by the different compliance options for the TPMS telltale(s) will be clear and apparent to most drivers. However, if any confusion arises, the first time the warning is encountered, the driver would be expected to consult the owner's manual to clarify the matter.

We are not adopting NADA's recommendation to have a single TPMS telltale that would require the driver to run through a hierarchy of diagnostics to determine what type of problem is causing the telltale to illuminate. We envision significant driver frustration with such an approach, particularly in those cases where the telltale remains illuminated after pressure check and

correction. This scenario can be avoided by setting a performance requirement that differentiates between low tire pressure situations and TPMS malfunctions.

In response to BERU's request for clarification, we note that the final rule requires the TPMS MIL to remain illuminated until such time as the condition causing the malfunction has been corrected. Accordingly, the MIL must remain illuminated while the system is running any validation protocols to determine whether the problem has been resolved, as the telltale is permitted to extinguish only after the TPMS can confirm that the system is again fully operational.

In response to EnTire's question, if the vehicle manufacturer elects to incorporate both of the TPMS low tire pressure telltales, it is only necessary to include a malfunction indicator in one of those telltales. Requiring both telltales to indicate a malfunction would not only be redundant, but it would also unnecessarily increase the amount of flashing experienced by the driver. We leave it to the manufacturer's discretion to choose in which of the two telltales the MIL should be incorporated.

Regarding Fuji's comment that the MIL should flash in certain circumstances and be continuously illuminated in other circumstances (depending upon the type of malfunction), we have decided not to adopt that recommendation. We are concerned that having different types of malfunction warnings within the same system could lead to consumer confusion. In order to detect malfunctions in all TPMS components, some additional circuitry and software logic may be required, as compared to current designs. We recognize that a failure of the control unit would be difficult to detect without appropriate circuitry and logic. Nevertheless, we believe that such a requirement for a flashing MIL would be practicable and achievable for all types of malfunctions.

(b)

Telltale Symbols for Low Pressure Warning and Malfunction Indication.

Several commenters stated that the proposed symbols for low tire pressure and TPMS malfunction are difficult to distinguish and, therefore, potentially confusing. Emtop argued that to the extent that the symbols are confused, drivers may delay taking the appropriate remedial action, and it further stated that misunderstood telltales could undermine confidence in the TPMS.

In its comments, the Alliance challenged statements in the NPRM indicating that the proposed symbol for the TPMS MIL could be recognized by consumers or that it would help achieve the desired response. The Alliance argued that the TPMS Docket does not provide documentation of the agency's evaluation of possible icons or the results of any focus group evaluation or study of such icons. The Alliance also stated that the proposed MIL icon is not consistent with the approach to other ISO standards, which indicate malfunctions by adding an exclamation point symbol (“!”). Accordingly, the Alliance argued that, in this instance, the MIL would require the addition of another exclamation point (“!”) on the side of the low tire pressure symbol. The Alliance commented that it is not aware of any ISO symbol attributing a meaning to the dashed element found in the NPRM's proposed TPMS MIL symbol, and instead, it suggested an alternate symbol (

i.e.

, the low tire pressure icon with the capital letters “TPM” in the middle).

Honda also recommended modifying the proposed TPMS malfunction warning telltale. Honda stated that the proposed malfunction symbol is new and not an internationally recognized symbol for TPMS malfunction, so Honda argued that there is latitude for a change. It recommended using the word “TPMS” for the system malfunction telltale. (Hyundai provided a similar comment.)

VW/Audi suggested that for the malfunction indicator, a more meaningful TPMS malfunction symbol might utilize the low tire symbol with a diagonal bar across it, a feature that is generally interpreted as the negative of the underlying symbol.

ETV expressed support for the proposed TPMS telltale that has the outline of a car with lighted indicators at each tire that can provide tire-specific information by referencing its installed location. ETV commented that, as opposed to the proposed ISO telltale design (which ETV referred to as the “cutaway tire”), the alternate symbol provides a “common sense” and readily recognizable symbol for low tire pressure, which would leave the car symbol's roof area available for the TPMS malfunction signal. ETV urged NHTSA to require that the visual telltale be supplemented with an audible alarm.

Advocates stated that the final rule should only permit the low tire pressure telltale that is capable of alerting the driver as to which tire is under-inflated, because motorists may not respond appropriately to re-inflate their tires unless they can tell which tire(s) is (are) under-inflated. Advocates argued that NHTSA has not provided any data regarding how consumers will react to a warning telltale that does not indicate which tire is under-inflated.

In the final rule, we have decided to adopt the NPRM's symbols for low tire pressure, but we have decided to change the requirement for the MIL symbol. For the low tire pressure warning, an internationally recognized symbol has been developed by ISO, and we are adopting that symbol as one of the options under FMVSS No. 101. In addition, we are providing an option for a telltale with a car symbol that would allow the TPMS to indicate which tire(s) is (are) significantly under-inflated by illuminating the corresponding tire on the telltale, which we believe would be readily understandable and also provide additional useful information to the driver. These symbols may be supplemented by the words “Low Tire.”

We are not expressing any preference between these two symbols. Not all TPMSs may be able to distinguish and identify which tire is significantly under-inflated, and we expected that if the low tire pressure telltale were to illuminate, most drivers would check and adjust the pressure in all of their tires. Further, the Advocates did not provide any data to demonstrate that the consumers would be confused by ISO's international symbol for low tire pressure. Therefore, in order maintain a technology-neutral standard, we are adopting the NPRM's two options for the TPMS low tire pressure symbol.

Regarding the symbol for the TPMS malfunction indicator using a separate telltale, we have decided to modify the requirements proposed in the NPRM. (For those systems providing a combined low tire pressure/TPMS malfunction warning in a single telltale, no additional symbol is required because malfunction is indicated by the flashing sequence discussed above.) Several commenters stated that the ISO symbol for low tire pressure and NHTSA's proposed symbol for the MIL were so similar as to be confusing. In addition, as noted by Honda and Emtop, there is not any internationally recognized symbol for TPMS malfunction, so the agency has latitude in selecting an appropriate symbol for the MIL.

We agree that the TPMS-related telltales should be sufficiently distinct and comprehensible, so as to facilitate proper driver response in both low tire pressure and TPMS malfunction situations. Accordingly, consistent with the recommendations of Honda and Hyundai in their comments, we have decided that for dedicated TPMS malfunction telltales, the telltale must display the word “TPMS,” without any symbol. We understand that the term “TPMS” is becoming commonly known, and, because it references the system

itself, it is distinct from the low tire pressure warning. We do not believe that VW/Audi's suggested approach of having the low pressure symbol inside a circle with a diagonal slash through it would provide sufficient clarification. In the event that the International Standards Organization (ISO), the Society of Automotive Engineers (SAE), or some other voluntary standards organization develops a symbol for TPMS malfunction, the agency would carefully evaluate such symbol and consider migration to the consensus standard as part of a subsequent rulemaking. We will carefully evaluate the distinctness and comprehensibility of any such symbol.

We are not adopting ETV's recommendation that we require an audible alarm to accompany the TPMS telltale(s), because we believe that the requirements of the final rule provide an adequate warning to the driver.

(c)

Telltale Color.

(i)

Low Pressure Warning Telltale.

The NPRM proposed to require a yellow telltale to indicate to the driver when a tire becomes significantly under-inflated (

see

Table 2 of FMVSS No. 101).

BMW commented that manufacturers should be permitted (but not required) to change the TPMS low pressure telltale from yellow to red once tire pressure becomes “extremely low.” BMW recommended that the TPMS should be allowed to change from yellow to red once the tire(s) drop 50 percent or more below placard pressure, a point at which the tire can be considered functionally flat. In its comments, BMW emphasized that this feature is particularly important for run-flat tires, because a consumer may not be able to determine by visual inspection or by handling feedback that the tire is flat. According to BMW, run-flat tires are designed to be driven with a loss of inflation pressure, but only at low speeds and for a limited distance; therefore, the consumer must be advised not to continue driving for an extended period of time or at highway speeds.

VW/Audi and Emtop provided similar comments about permitting the low tire pressure warning to change from yellow to red at a specified point. VW/Audi asserted that this functionality is desirable, both as a matter of safety (

i.e.

, to provide a heightened level of alert to indicate that the risk of tire failure is at a higher level) and as a matter of practicability (

i.e.

, to permit a single location for the basic warning indicator and the heightened red alert).

ETV also suggested linking a change in telltale color to a change in tire pressure, although at a much earlier point than other commenters. Specifically, ETV recommended requiring illumination of a yellow telltale when a tire is 20 percent below placard pressure, but changing the color to red (with an accompanying beep) when the pressure drops to 25 percent below placard pressure. ETV argued that this color change would not confuse drivers and that it may encourage more immediate action to remedy the under-inflation situation.

For the final rule, we have decided to adopt the NPRM's proposed requirement for a yellow low tire pressure telltale. The issues of the appropriate telltale color and the possibility of changing from one color to another have been raised in earlier rounds of this rulemaking, and the commenters on the NPRM have largely reiterated arguments raised previously. The following summarizes our reasoning for the yellow color requirement.

As we noted in the NPRM, we believe that yellow is the most appropriate color for the low tire pressure telltale. The use of the color red is usually reserved for telltales warning of an imminent safety hazard. An example is the brake system warning telltale, which is red because a failure in the vehicle's brake system results in an imminent safety hazard that requires immediate attention. In contrast, NHTSA requires a yellow telltale for driver warnings when the safety consequences of the malfunctioning system do not constitute an emergency and the vehicle does not require immediate servicing. Based upon the results of the agency's tire testing, we have concluded that yellow is the appropriate color for the low tire pressure telltale because it conveys the intended message that the driver may continue driving, but should check and adjust the tire pressure at the earliest opportunity.

To respond to the commenters' requests that NHTSA permit a telltale that changes color from yellow to red, we are concerned that this could confuse consumers, particularly if it is left to the discretion of individual vehicle manufacturers to decide the level of under-inflation at which the red telltale is triggered. Conceivably, it would be possible for a vehicle manufacturer to program the TPMS to illuminate a yellow telltale for a fraction of a second, after which time, it would immediately turn red; such a requirement would meet the letter of the requirement, but foil its intent.

As a counterpoint to ETV's argument, we believe that it is possible that if a driver knows that the TPMS low tire pressure warning will eventually shift from yellow to red, that person may elect to postpone taking remedial action until that time, a result quite contrary to that which is intended. It is conceivable that such drivers might actually take corrective action more quickly if they know that the illumination of the yellow low tire pressure telltale is the only warning that they will receive. However, in any case, we expect that such delayed action would be the anomalous response.

Therefore, although we are retaining the yellow color requirement for the low tire pressure telltale, we have decided that vehicle manufacturers may supplement the required low pressure telltale with an additional warning. For example, vehicle manufacturers may choose to incorporate a second, red lamp to accompany the continuously-illuminated yellow low tire pressure telltale. This red lamp could be illuminated when the pressure in one or more tires becomes dangerously under-inflated, as defined by the vehicle manufacturer. This approach is consistent with our traditional practice of allowing manufacturers to incorporate measures, consistent with Federal motor vehicle safety standards, which are designed to further enhance safety. If a vehicle manufacturer chooses to add a second, red warning lamp, its meaning and function would have to be discussed in the vehicle owner's manual.

We are not adopting ETV's suggestion for requiring an audible beep when tire inflation pressure drops to some point lower than 25 percent below placard pressure, because the commenter has not provided any evidence to show that this redundant warning signal is necessary. Likewise, we are not adopting ETV's recommendation for a 20-percent under-inflation threshold, for the reasons discussed above.

(ii)

Malfunction Indicator Telltale.

The NPRM proposed to require the color for the MIL to be yellow, regardless of whether it is incorporated in a combined telltale with the low tire pressure warning or is provided as a separate, dedicated telltale. For the combined telltale, the proposed MIL color requirement would carry through from the low tire pressure telltale's color requirement, and for the dedicated MIL, the proposed color requirement was set forth in Table 2 of FMVSS No. 101.

In its comments, the Alliance expressed support for requiring the dedicated TPMS malfunction indicator telltale to be yellow, to be constantly illuminated as long as the malfunction exists, and to perform a bulb check as required for other telltales.

ETV stated its belief that a systemic failure of the TPMS should illuminate a

red warning telltale, because the gravity of this situation is on par with a tire failure.

In the final rule, we are adopting a yellow color requirement for the MIL, both for the combined telltale and separate telltale options. As noted under the earlier discussion of the MIL, we do not believe that a TPMS malfunction constitutes an inherently dangerous situation requiring immediate corrective action, and just because the TPMS is malfunctioning, it does not necessarily mean that the vehicle's tires are under-inflated. Thus, if a yellow telltale is appropriate for the low tire pressure warning, we do not believe that there is justification for a more stringent warning for the TPMS MIL, as would be indicated by the color red.

(d)

Telltale Extinguishment Requirements.

Under S4.2(b), the NPRM proposed to require that the low pressure telltale “must extinguish after the inflation pressure is corrected.” Similarly, under S4.4(a), the NPRM proposed to require that the TPMS malfunction telltale “extinguishes when the malfunction has been corrected.”

Continental Teves commented that S4.2 is not technology-neutral because it does not provide for systems requiring manual reset (

e.g.

, hybrid systems). It recommended that the final rule permit the telltale to stay illuminated until the low-pressure situation has been corrected and the system has been reset in accordance with any applicable instructions in the owner's manual.

Schrader expressed concern that drivers will use TPMS reset buttons to extinguish the low pressure warning lamp without correcting the tire inflation problem, in order to extinguish the “annoying” telltale. In order to prevent such occurrences, Schrader stated that the final rule should not permit TPMSs with a manual reset feature that would allow consumers to recalibrate the system.

Emtop stated that the low tire pressure warning should not be extinguished until the tire pressure is at least 10 percent above the level specified in S4.2(a) of the NPRM.

We disagree with the comments of Continental Teves, which stated that S4.2 is not technology-neutral because that section does not specifically mention that the TPMS will be reset in accordance with any applicable instructions in the vehicle owner's manual. Although system reset was not specifically mentioned in S4.2, it is clearly addressed in S6(c), S6(i), S6(j), and S6(1) of the test procedures. However, in order to foster a better understanding of this provision, we have provided additional clarifying language in S4.2 of the final rule.

We agree with Schrader that drivers should not reset the TPMS so as to extinguish the low tire pressure warning telltale (or the MIL) until the underlying problem has been corrected (

e.g.

, restoring proper inflation pressure or remedying other problems). We believe that vehicle manufacturers will clearly address this issue when explaining the TPMS reset feature, if applicable. We believe that no additional language is necessary on this point.

As to Emtop's recommendation that we should require the tires to be refilled to at least 10 percent above the level specified in S4.2(a) of the NPRM before permitting the telltale to extinguish, we do not believe that such a requirement is necessary. First, if a tire i

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