Interpretation ID: nht89-1.4

TYPE: INTERPRETATION-NHTSA

DATE: 01/18/89

FROM: ERIKA Z. JONES -- CHIEF COUNSEL NHTSA

TO: WENDELL D. KEGG -- TIRE WHEEL CONSULTANTS

TITLE: NONE

ATTACHMT: LETTER DATED 09/14/88 FROM WENDELL D. KEGG TO ERIKA Z. JONES -- NHTSA, OCC 2560

TEXT: Dear Mr. Kegg:

This responds to your letter seeking an interpretation of Federal Motor Vehicle Safety Standard No. 110, Tire Selection and Rims. You were uncertain about section S4.3.1's requirements related to the inflation pressure for spare tires specified on vehic le placards. You asked whether a vehicle manufacturer can specify a higher inflation pressure for a spare tire than the maximum inflation pressure molded on the tire's sidewall.

As you know, FMVSS 110 sets forth requirements related to vehicle placards in passenger cars. Section S4.3 requires that the placard be "permanently affixed to the glove compartment door or an equally accessible location" and display the vehicle capacit y weight; the designated seating capacity; the vehicle manufacturer's recommended cold tire inflation pressure for maximum loaded weight and, subject to the limitations of S4.3.1, for any other manufacturer-specified vehicle loading condition; and the ve hicle manufacturer's recommended tire size designation. FMVSS 110 does not have any provision requiring the inclusion of information on the placard related to spare tires or air pressure related to spare tires. Accordingly, a passenger car manufacturer may, but is not required to, specify information related to spare tires on the placard.

In response to your question whether a passenger car manufacturer can specify a higher inflation pressure for a spare tire than the maximum inflation pressure molded on the spare tire's sidewall, section S4.3.1 of FMVSS 110 states that the vehicle placar d must not specify an "inflation pressure other than the maximum permissible inflation pressure" required to be molded on the tire itself by section S4.3 of FMVSS 109, New Pneumatic Tires, unless the alternative inflation pressure satisfies the three con ditions set forth in S4.3.1. The first condition requires that the alternative inflation pressure be less than the maximum permissible inflation pressure. The second condition requires that the vehicle loading condition be specified for the alternative reduced pressure. The third condition requires that the tire load rating be specified by an individual manufacturer for the tire size at that inflation pressure that

is not less than the vehicle load on the tire for that vehicle loading condition. Accordingly, a vehicle manufacturer could not specify on its placard an inflation pressure that exceeds the maximum permissible inflation pressure.

I am enclosing a December 13, 1984 letter to Mr. Alberto Negro of Fiat, which explains the agency's position concerning a manufacturer's specification on the placard of an inflation pressure that exceeds the maximum inflation pressure molded on the tire. As that letter indicates, a manufacturer would have to meet each of the conditions specified in section S4.3.1, including that the alternative inflation pressure must be less than the maximum permissible inflation pressure. Because spare tires are sub ject to these requirements like any other pneumatic tire, a vehicle manufacturer could not specify a higher inflation pressure for a spare tire than the maximum inflation pressure molded on that tire.

If you have any further questions or need additional information on this subject, please feel free to contact Marvin Shaw of my staff at this address or by telephone at (202) 366-2992.

Sincerely,

ENCLOSURE