2014 Chevrolet Express 3500 Passenger Owner Manual - Page 302

10-52 Vehicle Care (6) Load Range: Load Range. (7) Service Description: The service description indicates the load index and speed rating of a tire. If two numbers are given as in the example, 120/116, then this represents the load index for single versus dual wheel usage (single/dual). The speed rating is the maximum speed a tire is certified to carry a load. This does not apply to Goodyear LT225/75R16 G949 RSA and Goodyear LT225/75R16 G933 RSD commercial truck tires; see the dual tire and single tire maximum load and load range letter designations on the tire sidewall. (3) Aspect Ratio: A two-digit number that indicates the tire height-to-width measurements. For example, if the tire size aspect ratio is 75, as shown in item 3 of the light truck (LT-Metric) tire illustration, it would mean that the tire's sidewall is 75 percent as high as it is wide. (4) Construction Code: A letter code is used to indicate the type of ply construction in the tire. The letter R means radial ply construction; the letter D means diagonal or bias ply construction; and the letter B means belted-bias ply construction. (5) Rim Diameter : Diameter of the wheel in inches. Tire Terminology and Definitions Air Pressure: The amount of air inside the tire pressing outward on each square inch of the tire. Air pressure is expressed in kPa (kilopascal) or psi (pounds per square inch). Accessory Weight: The combined weight of optional accessories. Some examples of optional accessories are automatic transmission, power windows, power seats, and air conditioning. Aspect Ratio: The relationship of a tire's height to its width. Belt: A rubber coated layer of cords between the plies and the tread. Cords may be made from steel or other reinforcing materials.