1997 Pontiac Sunfire Owner's Manual - Page 288

Uniform Tire Quality Grading The following information relatesto 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 vehiclessold in the United States.)The grades aremolded 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 temporaryuse spare tires, tires with nominal rim diameters of 10 to 12 inches (25 to 30 cm), or to some limited-production tires. While the tiresavailable on General Motors passenger cars and light trucks may vary with respect to these grades, they mustalso conform to Federal safety requirements and additional General Motors Tire Performance Criteria (TPC) standards. Peadwear The treadwear grade isa comparative rating based on the wear rateof the tire when tested undercontrolled conditions on a specified government test course. For example, a tire graded 150 would wear one and a half (1 1/2) times as 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 significantlyfrom the norm due to variations in driving habits,service practices and differences in road characteristics and climate. Traction A, B, C The traction grades, fi-om highest to lowest, are A, B, and C, and they represent the tire's ability to stop wet on pavement as measured under controlled conditions on specified government test surfacesof asphalt and concrete. A tire markedC may have poor traction performance. Warning: The traction grade assigned to this tire is based on braking (straightahead) traction tests and does not include cornering (turning) traction. -- 6-44