2008 Mercedes R-Class Owner's Manual - Page 388

Operation Tires and wheels At the tire manufacturer's option, any tire with a speed capability above 149 mph (240 km/h) can include a "ZR" in the size designation (for example: 245/40 ZR18). To determine the maximum speed capability of the tire, the service description for the tire must be referred to. The service description is comprised of the tire load rating 5 ( page 384) and the tire speed rating 6 ( page 384). If your tire includes "ZR" in the size designation and no service description 5 and 6 ( page 384) is given, the tire manufacturer must be consulted for the maximum speed capability. If a service description 5 and 6 ( page 384) is given, the speed capability is limited by the speed symbol in the service description. Example: 245/40 ZR18 97Y. In this example, "97Y" is the service description. The letter "Y" designates the speed rating and the speed capability of the tire is limited to 186 mph (300 km/h). Any tire with a speed capability above 186 mph (300 km/h) must include a "ZR" in the size designation AND the service description must be placed in parenthesis. Example: 275/40 ZR 18 (99Y). The "(Y)" speed rating in parenthesis designates the maximum speed capability of the tire as being above 186 mph (300 km/h). Consult the tire manufacturer for the actual maximum permissible speed of the tire. All-season and winter tires Index Q M+S1 1 1 Speed rating up to 100 mph (160 km/h) up to 118 mph (190 km/h) up to 130 mph (210 km/h) up to 149 mph (240 km/h) T M+S H M+S V 1 M+S1 or M+S . for winter tires i Not all M+S rated radial-ply tires provide special winter performance. Make sure the tires you use show M+S and the mountain/snowflake . marking on the tire sidewall. These tires meet specific snow traction performance requirements of the Rubber Manufacturers Association (RMA) and the Rubber Association of Canada (RAC) and have been designed specifically for use in snow conditions. 387