1993 Pontiac Firebird Owner's Manual - Page 258

Warning: The temperature grade for this tire is establishedfor a tire that is properly inflated and not overloaded. Excessive speed, underinflation,or excessive in loading, either separately or combination, can cause heat buildup and possible tire failure. Those grades are molded on the sidewalls of passenger car tires. While the tires available as standard or optional equipment on General Motors vehicles may vary with respectto these grades, all such tires meet General Motors performance standards and have been approved for use on General Motors vehicles. All passenger type (P Metric) tires must conform to Federal safety requirements in addition to these grades. 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. In most cases, you will not need to have your wheels aligned again. However, if you notice unusual tire wear or your vehicle pulling one way or the other, the alignment may need to be reset. If you notice your vehicle vibrating when driving on a smooth road, your wheels may need to be rebalanced. 257 9 9