2009 Mercedes SLR McLaren Owner's Manual - Page 277

Operation Tires and wheels Tire size designation, load and speed rating General: Depending on the design standards used, the tire size molded into the sidewall may have no letter or a letter preceding the tire size designation. No letter preceding the size designation (as illustrated above): Passenger car tire based on European design standards. Letter "P" preceding the size designation: Passenger car tire based on U.S. design standards. 1 Tire width 2 Aspect ratio in % 3 Radial tire code 4 Rim diameter 5 Tire load rating 6 Tire speed rating Letter "LT" preceding the size designation: Light Truck tire based on U.S. design standards. Letter "T" preceding the size designation: Temporary spare tires which are high pressure compact spares designed for temporary emergency use only. Tire width The tire width 1 ( page 277) indicates the nominal tire width in mm. Aspect ratio The aspect ratio 2 ( page 277) is the dimensional relationship between tire section height and section width and is expressed in percentage. The aspect ratio is arrived at by dividing section height by section width. Tire code The tire code 3 ( page 277) indicates the tire construction type. The "R" stands for radial tire type. Letter "D" means diagonal or bias ply construction; letter "B" means belted-bias ply construction. 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 ZR 18). For additional information, see "Tire speed rating" ( page 279). i For illustration purposes only. Actual data on tires is specific to each vehicle and may vary from data shown in above illustration. 277