Know Your Tires
"89H" in this example, consists of the load index (89) and speed symbol (H). This only appears on speed-rated tires
The "P" in front of the number stands for "passenger." "215" represents the width of the tire in millimeters. "65" is the ratio of height to width. The "R" stands for "radial" and the "15" is the diameter of the wheel in inches. A "B" in place of the "R" means the tire is belted bias construction. A "D" in place of the "R" means diagonal bias construction.
The treadwear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test track. A tire graded 200 would wear twice as long on the government test course under specified test conditions as one graded 100. Traction grades, from highest to lowest, are A, B and C. They represent the tire's ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces of asphalt and concrete. The temperature grades, from highest to lowest, are A, B and C. These represent the tire's resistance to the generation of heat when tested under controlled conditions on a specified indoor laboratory test wheel.
The maximum load is shown in lbs. (pounds) and in kg (kilograms), and maximum pressure in psi (pounds per square inch) and in kPa (kilopascals). Kilograms and kilopascals are metric units of measurement.
The sidewall also shows the type of cord and number of plies in the sidewall and under the tread. The DOT requires tire manufacturers to grade passenger car tires based on three performance factors: treadwear, traction and temperature resistance.
The letters "DOT" certify compliance with all applicable safety standards established by the Department of Transportation (DOT). Adjacent to this is a tire identification or serial number. This serial number is a code with up to 11 digits that are a combination of numbers and letters.
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