2005 Mercedes CLK-Class Owner's Manual - Page 338

Operation Tires and wheels Uniform Tire Quality Grading Standards (U.S. vehicles) Tire manufacturers are required to grade tires based on three performance factors: treadwear, traction and temperature resistance. Quality grades can be found, where applicable, on the tire sidewall between tread shoulder and maximum section width. For example: Treadwear Traction Temperature 200 AA A from the norm due to variations in driving habits, service practices and differences in road characteristics and climate. Traction The traction grades, from highest to lowest, are AA, A, B, and C. Those grades represent the tire's ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces of asphalt and concrete. A tire marked C may have poor traction performance. Warning! All passenger car tires must conform to federal safety requirements in addition to these grades. 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, a tire graded 150 would wear one and one-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 conditions of their use, however, and may depart significantly G 1 Treadwear 2 Traction 3 Temperature resistance i For illustration purposes only. Actual data on tires is specific to each vehicle and may vary from data shown in above illustration. The traction grade assigned to this tire is based on straight-ahead braking traction tests, and does not include acceleration, cornering, hydroplaning, or peak traction characteristics. 336