2014 Buick Verano Owner Manual - Page 298

10-44 Vehicle Care (5) Tire Inflation: The temporary use tire or compact spare tire should be inflated to 420 kPa (60 psi). For more information on tire pressure and inflation see Tire Pressure on page 10-47. (6) Tire Size: A combination of letters and numbers define a tire's width, height, aspect ratio, construction type, and service description. The letter T as the first character in the tire size means the tire is for temporary use only. (7) TPC Spec (Tire Performance Criteria Specification): Original equipment tires designed to GM's specific tire performance criteria have a TPC specification code molded onto the sidewall. GM's TPC specifications meet or exceed all federal safety guidelines. Tire Designations Tire Size The following is an example of a typical passenger vehicle tire size. (3) Aspect Ratio: A two-digit number that indicates the tire height-to-width measurements. For example, if the tire size aspect ratio is 60, as shown in item 3 of the illustration, it would mean that the tire's sidewall is 60 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. (6) Service Description: These characters represent the load index and speed rating of the tire. The load index represents the load carrying capacity a tire (1) Passenger (P-Metric) Tire: The United States version of a metric tire sizing system. The letter P as the first character in the tire size means a passenger vehicle tire engineered to standards set by the U.S. Tire and Rim Association. (2) Tire Width: The three-digit number indicates the tire section width in millimeters from sidewall to sidewall.