GM Service Manual Online
For 1990-2009 cars only

Object Number: 182126  Size: SH

The tires on all new production models have a tire performance criteria (TPC) rating number molded on the sidewall. The TPC rating will appear as a 4-digit number preceded by the letters TPC SPEC on the tire wall near the tire size. A replacement tire should have the same TPC rating.

Tire Wear


Object Number: 386773  Size: SF
(1)Hard Cornering/Underinflation
(2)Incorrect Alignment/Lack of Rotation
(3)Incorrect Alignment/Non-uniform Tire
(4)Heavy Acceleration/Over inflation
(5)Wear Indicator

Inspect the tire and wheel assemblies for the following conditions:

    • Unusual wear such as cupping, flat spots, and/or heel-and-toe wear
        These conditions can cause tire growl, tire howl, slapping noises, and/or vibrations throughout the vehicle.
    • Proper inflation to specifications for the vehicle
    • Bulges in the sidewalls
        Do not confuse bulges, which are an abnormal condition, with normal ply splices which are commonly seen as indentations in the sidewall.
    • Bent rim flanges