1997 Buick Riviera Owner's Manual - Page 284

I Mlxmg tires could cause to lose control while you driving. If you mix tires of different sizes or types (radial andbias-belted tires), the vehicle may not handle properly, and you could havea crash. Using tires of different sizes may also cause damage to your vehicle. Be sure touse the same size and type tires on all wheels. It's all right to drive with your compact spare, though. It was developed for use on yourvehicle. 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 to cars and light trucks may vary with respectthese grades, they must also conform to Federal safety requirements and additional General Motors Tire Performance Criteria (TPC) standards. Treadwear on The treadwear grade is a comparative rating based the wear rate of the tire when tested under controlled conditions on a specified government test course. For 150 example, a tire graded would wear one and a half (1 1/2) timesas well on the government course as a tire graded 100. The relative performance of tires depends upon the actual conditionsof their use, however, and may depart significantly from the norm to variations due in in driving habits, service practices and differences road characteristics and climate. Uniform Tire QualityGrading The following information relates to the system developed bythe United States National Highway Traffk Safety Administration, which grades tires by treadwear, traction and temperature performance. (This applies only to vehicles sold the United States.) The in grades are molded the sidewalls of most passenger on 6-47