1998 Pontiac Trans Sport Owner's Manual - Page 373

Uniform Tire Quality Grading Mixing tires couldcause you to lose control while driving. If you mix tires of different sizes or types (radial and bias-belted tires), the vehicle may not handle properly, and you could have a crash, cause Using tires of different sizes may also damage to your vehicle. Be sure to use the same size and type tires on all wheels. It's all right to drivewith your compact spare, though. It was developed for use on your vehicle. The following information relates to the system developed by the United States National Highway Traffic Safety Administration, which grades tires by treadwear, traction and temperature performance. (This applies only to vehicles sold in the United States.) The grades are molded on the sidewalls of most passenger car tires. The Uniform Tire Quality Grading system does not apply to deep tread, winter-type snow tires, space-saver or temporary use spare tires, tires with nominal rim 'diameters of 10 to 12 inches (25 to 30 cm), or to some limited-production tires. While the tires available on General Motors passenger cars and light trucks may vary with respect to these grades, they must also conform to Federal safety requirements and additional General Motors Tire Performance Criteria (TPC) standards. If you use bias-ply tires on your vehicle, the wheel rim flanges could developcracks after many miles of driving. A tire and/orwheel could fail suddenly, causing a crash. Use only radial-ply tires with the wheels on your vehicle. 6-44