Uniform Tire Quality GradingQuality grades can be found where applicable onthe tire sidewall between tread shoulder andmaximum section width. For example:Treadwear 200 Traction AATemperature AThe following information relates to the systemdeveloped by the United States National HighwayTraffic Safety Administration (NHTSA), whichgrades tires by treadwear, traction, andtemperature performance. This applies only tovehicles sold in the United States. The grades aremolded on the sidewalls of most passenger cartires. The Uniform Tire Quality Grading (UTQG)system does not apply to deep tread, winter-typesnow tires, space-saver, or temporary usespare tires, tires with nominal rim diameters of10 to 12 inches (25 to 30 cm), or to somelimited-production tires.While the tires available on General Motorspassenger cars and light trucks may vary withrespect to these grades, they must also conformto federal safety requirements and additionalGeneral Motors Tire Performance Criteria (TPC)standards.TreadwearThe treadwear grade is a comparative ratingbased on the wear rate of the tire when testedunder controlled conditions on a specifiedgovernment test course. For example, a tiregraded 150 would wear one and a half (1.5) timesas well on the government course as a tiregraded 100. The relative performance of tiresdepends upon the actual conditions of their use,however, and may depart significantly fromthe norm due to variations in driving habits, servicepractices, and differences in road characteristicsand climate.Traction – AA, A, B, CThe traction grades, from highest to lowest, areAA, A, B, and C. Those grades represent the tire’sability to stop on wet pavement as measuredunder controlled conditions on specifiedgovernment test surfaces of asphalt and concrete.A tire marked C may have poor tractionperformance.6-67
