2009 Mercedes CLK-Class Owner's Manual - Page 255

Operation Tires and wheels Uniform Tire Quality Grading Standards The Uniform Tire Quality Grading is a U.S. Government requirement designed to give drivers consistent and reliable information regarding tire performance. Tire manufacturers are required to grade tires based on three performance factors: treadwear, traction, and temperature resistance. Although not a Government of Canada requirement, all tires made for sale in North America have these grades branded on the sidewall. service practices and differences in road characteristics and climate. i For illustration purposes only. Actual data on tires are specific to each vehicle and may vary from data shown in above illustration. Quality grades can be found, where applicable, on the tire sidewall between tread shoulder and maximum section width. For example: Treadwear 200 Traction AA Temperature A Traction G Warning! 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. 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. 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 U.S. 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 from the norm due to variations in driving habits, G Warning! If ice has formed on the road, tire traction will be substantially reduced. Under such weather conditions, drive, steer and brake with extreme caution. The safe speed on a wet, snow covered or icy road is always lower than on a dry road. You should pay particular attention to the condition of the road whenever the outside temperature is close to the freezing point. 1 Treadwear 2 Traction 3 Temperature resistance Z 253