Interpretation ID: nht76-1.47

DATE: 11/17/76

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: Department of California Highway Patrol

TITLE: FMVSS INTERPRETATION

TEXT: This responds to your September 16, 1976, question whether any Federal regulation requires that the maximum load rating assigned to a passenger car tire be reduced by approximately 10 percent in calculating its maximum load rating for use on a multipurpose passenger vehicle (MPV), truck, or bus.

The answer to your question is yes. Standard No. 120, Tire Selection and Rims for Motor Vehicles Other than Passenger Cars, became effective September 1, 1976, and provides for the reduced maximum load rating you describe. Section S5.1.2 of the standard provides in part that "[when] a tire listed in [the passenger car tire standard] is installed on a multipurpose passenger vehicle, truck, bus, or trailer, the tire's load rating shall be reduced by dividing by 1.10 before calculating the sum [that must at least equal the axle system's gross axle weight rating]." A copy of the standard, with subsequent amendments, is enclosed for your information.

SINCERELY,

DEPARTMENT OF CALIFORNIA HIGHWAY PATROL

September 16, 1976

John W. Snow National Highway Traffic Safety Administration

We have noted that page XI of the 1976 Tire and Rim Association standards, copy enclosed, requires that a passenger car tire be loaded to not more than 91 percent of its rated load when used on a truck, bus or multipurpose passenger vehicle. Is this limitation included as a part of Federal Motor Vehicle Safety Standards Nos. 109 or 119?

If the requirement is applicable, we propose to include it in our Vehicle Equipment Inspection Guide. If the restriction is not referenced in the standard, are we preempted from adopting it as a part of the enclosed State regulations on tires?

WARREN M. HEATH Commander Engineering Section