Goodyear tire size charts include tire type, tire width, aspect ratio and rim diameter. Instructions for determining how much load a tire can support and the maximum speed a tire can handle are also available on the Goodyear Tires official website.
Tire specifications appear on the tire's sidewall in a specific order from left to right, beginning with a letter indicating the type of tire. For example, P indicates a passenger car and LT indicates a light truck. Tire width from sidewall to sidewall is provided in millimeters. Aspect ratio, which follows width, compares the height of the cross-section of the tire with its width. If the number on the tire is 55, it indicates that the height of the tire is 55 percent of its width.
Rim diameter follows either an R (radial) or B (bias) designating the type of tire construction. Rim diameter is the width of the wheel from end to end and is presented in either inches or centimeters. When replacing tires, Goodyear advises using only tires with exactly the same rim diameter.
Goodyear tire size charts also include load index and speed rating. The load index range for passenger cars begins at 75, which supports a load of 852 pounds. Speed ratings are noted by letters indicating maximum speeds.