1997 GMC Savana Van Owner's Manual - Page 280

grades, they mustalso conform to Federal safety requirements and additional General Motors Tire Performance Criteria (TPC) standards. Mixing tires could cause you to lose control while of driving. If you mix tires different sizes or types (radial and bias-belted tires), the vehicle may not you could have a crash. handle properly, and Using tiresof different sizes may also cause Be damage to your vehicle. sure to use the same on size and type tires all wheels. Treadwear The treadwear gradeis a comparative rating based on the wearrate of the tire when tested under controlled conditions on a specified government testcourse. For example, a tire graded 150 would wear one and half a (1 1/2) times as well on the government course as a tire graded .loo. The relative performance of tires depends upon the actual conditions of their use, however, and may depart significantly from the norm due to variations in driving habits, 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 appliesonly to vehicles sold in the United States.) The grades are molded on the sidewalls most passenger cartires. The Uniform of Tire Quality Grading system does not apply to deep tread, winter-type snow tires, space-saver or temporary use spare tires, tires with nominalrim 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 Traction -- A, B, C The traction grades, from highest to lowest, are B, and A, C, and they represent the tire's ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces asphalt and concrete. of A tire marked C 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. 6-46