1997 Pontiac Grand Prix Owner's Manual - Page 322

Temperature -- A, B, C Wheel Alignment and Tire Balance The wheels on your vehicle were aligned and balanced carefully at the factory to give you the longest tire life and best overall performance. Scheduled wheel alignment and wheel balancing are not needed. However, if you notice unusual tire wear or your vehicle pulling one way or theother, the alignment may need to bereset. If you notice your vehicle vibrating when driving on a smooth road, your wheels may need to berebalanced. The temperature grades are A (the highest), B, and C, representing the tire's resistance to the generation of heat and its ability to dissipate heat when tested under controlled conditions on a specified indoor laboratory test wheel. Sustained high temperature can cause the material of the tire to degenerate and reduce tire life, and excessive temperature can lead to sudden tire failure. The grade C corresponds to a level of Performance which all passenger car tires must meet under the Federal Motor Vehicle Safety Standard No. 109. Grades B and A represent higher levels of performance on the laboratory test wheel than the minimum required by law. Warning: The temperature grade for this tire is established for a tire that is properly inflated and not overloaded. Excessive speed, underinflation, or excessive loading, either separately or in combination, can cause heat buildup and possible tire failure. Wheel Replacement Replace any wheel that is bent, cracked, or badly rusted or corroded. If wheel nuts keep corning loose, the wheel, wheel bolts and wheel nuts should be replaced. If the wheel leaks air, replace it (except some aluminum wheels, which can sometimes be repaired). See your Pontiac dealer if any of these conditions exist. Your dealer will know the kind of wheel you need. Each new wheel should have the same load-carrying capacity, diameter, width, offset and be mounted the same way as the one it rep1,aces. 6-52