Interpretation ID: 2672y

Roger C. Fairchild, Esq.
Shutler & Low
14500 Avion Parkway, Suite 300
Chantilly, VA 22021-1101

Dear Mr. Fairchild:

This responds to your inquiry about Federal Motor Vehicle Safety Standards 109, 110, 119, and 120 on tires and rim selection (49 CFR 571.109, 571.110, 571.119, and 571.120), asking about the applicability of certain provisions in the Tire and Rim Association (TRA) Year Book, which those Federal safety standards incorporate by reference. As explained below, we agree that the adjustment factors in the TRA Year Book for inflation pressures and load ratings at different speeds are not applicable in determining compliance with Federal safety standards.

By way of background, the National Traffic and Motor Vehicle Safety Act, ("Vehicle Safety Act," 15 USC 1381 et seq.) requires every new motor vehicle sold in the United States to be certified as complying with all applicable Federal motor vehicle safety standards. The Vehicle Safety Act specifies that the manufacturer must certify that each of its vehicles complies with all applicable safety standards in effect on the date of manufacture. Because of this statutory requirement, this agency does not approve any manufacturer's vehicles or offer assurances that the vehicles comply with the safety standards. Any person violating the Vehicle Safety Act by manufacturing or selling new noncomplying vehicles may be liable for potential penalties of $1,000 per violation up to $800,000.

Section S4.3 of Standard 109 requires a new pneumatic tire for passenger cars to be labeled with certain information including one size designation, the maximum inflation pressure, and the maximum load rating. S6.5 of Standard 119 has similar marking requirements for tires on vehicles other than passenger cars. In particular, section 4.2.1(c) of Standard 109 and section 6.5(d) of Standard 119 require tires to be labeled with a maximum load rating not less than the lowest of any specified values in the manufacturer's submission or in a listed publication such as the TRA Yearbook, for tires of that size designation, type and each appropriate inflation pressure. For passenger car tires, these inflation pressures and load ratings are specified in tables in section one of the TRA Yearbook entitled, "'P' Type Tires Used on Passenger Cars and Station Wagons" and "'T' Type Spare Tires for Temporary Use on Passenger Cars and Station Wagons." For tires on vehicles other than passenger cars, these inflation pressures and load ratings are specified in the tables in section 2 of the TRA Yearbook. Question One You first asked whether the Federal safety standards incorporate an independent vehicle speed adjustment factor in determining the "vehicle normal load" and "vehicle maximum load." Your question was based on provisions in the TRA Year Book which apply such a vehicle load adjustment factor for certain tires rated for a maximum speed above 130 mph. As you are aware, S4.2 of Standard 110 provides that the vehicle maximum load on the tire shall not be greater than the applicable maximum load rating marked on the tire, and the vehicle normal load on the tire shall not be greater than the test load used in Standard 109's high speed performance test.

You are correct that an adjustment factor based on the vehicle's maximum speed capacity is not required to be used in determining compliance with Standard 110 and 120. As you noted, Standard 110's requirement, as specified in S4.2.2, takes into account an adjustment for high speed use by requiring that the normal vehicle load on a tire must not exceed the test load used in Standard 109's high speed performance test in S5.5 (i.e. 88 percent of the tire's maximum load rating). Based on this provision and Standard No. 110's use of the terms "vehicle maximum load" and "maximum loaded vehicle weight," we interpret S4.2 as applying to normal vehicle uses and not special high speed applications. In fact, incorporating a load adjustment factor based on speeds of 130 to 168 mph, as the TRA provision does, would be contrary to motor vehicle safety if it encouraged vehicle operation at speeds far exceeding safe operating speeds. Therefore, the general tables in the TRA Yearbook listing maximum inflation pressures and maximum load ratings, standing alone without applying any adjustment factor, are the applicable values in determining compliance with the Federal safety standards.

Question Two You also asked about a vehicle speed adjustment factor for the inflation pressure with passenger cars. As you explained, the TRA Year Book requires that the "speed category of the tire must match or exceed the theoretical maximum speed of the vehicle (i.e., actual maximum speed, as adjusted for tire inflation pressure using another factor specified by TRA). TRA sets forth two speed categories: speeds up to 210 km/h (130 mph) and speeds above 210 km/h (130 mph).

As with the vehicle load adjustment factor which concerns normal vehicle applications, you are correct that an adjustment factor for inflation pressure based on the vehicle's maximum speed is not required to be used in determining compliance with Federal safety standards. Again, the general tables in the TRA Yearbook listing maximum inflation pressures and maximum load ratings, standing alone without applying any adjustment factor, are the applicable values in determining compliance with the Federal safety standards.

Question Three You then asked about the applicability to the Federal standards of TRA's recommended adjustments for tire inflation pressure and "service load" for tires used on trucks and buses, depending on the maximum speed capability of the vehicle. As with the adjustment factors for passenger car tires, these adjustment factors are not relevant for compliance with Standard 119 or 120. Again, the general tables in the TRA Yearbook listing maximum inflation pressures and maximum load ratings, standing alone without applying any adjustment factor, are the applicable values in determining compliance with the Federal safety standards.

I hope this information is helpful. If you have any further questions, please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992.

Sincerely,

Paul Jackson Rice Chief Counsel

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