2008 Mazda RX-8 Owner's Manual - Page 336

Customer Information and Reporting Safety Defects Tire Information (U.S.A.) H "H" is the speed rating. The speed rating denotes the maximum speed for which the use of the tire is rated. Letter Rating Q R S T U H V W Y Speed Rating 99 mph 106 mph 112 mph 118 mph 124 mph 130 mph 149 mph 168* mph 186* mph * For tires with a maximum speed capability over 149 mph, tire manufacturers sometimes use the letters ZR. For tires with a maximum speed capability over 186 mph, tire manufacturers always use the letters ZR. M+S or M/S: Mud and Snow AT: All Terrain. AS: All Season. The "M+S" or "M/S" indicates that the tire has some functional use in mud and snow. U.S. DOT Tire Identification Number (TIN) This begins with the letters "DOT" which indicates the tire meets all federal standards. The next two numbers or letters are the plant code where it was manufactured, and the last four numbers represent the week and year the tire was manufactured. For example, the numbers 457 means the 45st week of 1997. After 2000 the numbers go to four digits. For example, the number 2102 means the 21th week of 2002. The other numbers are marketing codes used at the manufacturer's discretion. This information is used to contact consumers if a tire defect requires a recall. Tire Ply Composition and Materials Used The number of plies indicates the number of layers of rubber-coated fabric in the tire. In general, the greater the number of plies, the more weight a tire can support. Tire manufacturers also must indicate the tire materials, which include steel, nylon, polyester, and other. Maximum Load Rating This number indicates the maximum load in kilograms and pounds that can be carried by the tire. Maximum Permissible Inflation Pressure This number is the greatest amount of air pressure that should ever be put in the tire under normal driving conditions. 9-20