1998 GMC Safari Owner's Manual - Page 310

Temperature -- A, B, C Wheel Alignment and Tire Balance The wheels on your vehicle were aligned and balanced carefully at the factory give you the longest tire life to and best overall performance. Scheduled wheel alignment and wheel balancing are not needed. However, if you notice unusualtire wear or your vehicle pulling one way the other, the alignment or may need to be reset. If you notice your vehicle vibrating when driving on smooth road, your wheels a may needto be rebalanced. The temperature grades are (the highest), B, and C, A representing the tire's resistance to the generation of heat and its ability to dissipate heat when tested under controlled conditions on specified indoor laboratory a test wheel. Sustained high temperature can cause the material of the tire to degenerate and reduce tire and life, excessive temperature can lead to sudden tire failure. The gradeC corresponds to a level of performance which all passenger car tires must meet under the Federal Motor Vehicle Safety StandardNo. 109. Grades B and A represent higher levels performance of on the laboratory test wheel than the minimum required by law. Warning: The temperature gradefor 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 failure. tire Wheel Replacement Replace any wheel that bent, cracked, or badly rusted is or corroded. If wheel nuts keep coming loose, the wheel, wheel bolts and wheel nuts should be replaced. If the wheel leaks air, replace (except some aluminum it wheels, which can sometimes be repaired). See your dealer if any of theseconditions exist. 6-48