1996 Oldsmobile Achieva Owner's Manual - Page 263

Mixing tires could cause to lose control while you 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. Using tires of different sizes may also cause damage to your-vehicle. sure touse the same Be size and type tires on all four wheels. It's all-right to drive with your compact spare, though. It was developed for use on your vehicle. car tires. The Uniform Tire Quality Grading system does not apply to deep tread, winter-type snow tires, space-saver ortemporary use spare tires, tires with to nominal rim diametersof 10 to 12 inches (25 30 cm), or to some limited-production tires. While the tires available on General Motors passenger cars and light trucks may vary with respect tothese grades, they must also conform to Federalsafety requirements and additional General Motors Tire Performance Criteiia ( P C ) standards. Treadwear The treadwear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test course. For example, atire graded 150 would wear one and a half (1 1/2) times as well on the g o v e m e n t course as a tire graded 100. The relative performance of tires depends upon the actual conditions of their use, however, and may depart significantly from thenorm due to variations in drivinghabits, service practices and differences in road characteristics and climate. Uniform Tire Quality Grading 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 United States.) The the grades aremolded on the sidewalls of most passenger 6-41