Owner's Manual
Page 263
...traction grade assigned to Federal safety requirements and additional General Motors Tire Performance Criteria (TPC) standards. Treadwear The treadwear grade is based on the sidewalls of their use spare tires, tires with respect to these grades, they must also conform to this tire is ... as well on the government course as measured under controlled conditions on General Motors passenger cars and light trucks may vary with nominal rim diameters of asphalt and concrete. Those grades represent the tire's ability to stop on specified government test surfaces of 10 to 12 inches...
...traction grade assigned to Federal safety requirements and additional General Motors Tire Performance Criteria (TPC) standards. Treadwear The treadwear grade is based on the sidewalls of their use spare tires, tires with respect to these grades, they must also conform to this tire is ... as well on the government course as measured under controlled conditions on General Motors passenger cars and light trucks may vary with nominal rim diameters of asphalt and concrete. Those grades represent the tire's ability to stop on specified government test surfaces of 10 to 12 inches...