How to Read a Tire

Your tire contains very useful information molded into the sidewall.  It shows the name of the tire, its size, whether it is tubeless or tube type, the maximum load and maximum inflation, the important safety warning and much other information.  I hope you find this handy information useful. Shown below is the sidewall of a typical "P-metric," (P215/65R15 89H) speed-rated tire.

● P stands for passenger tire;
● 215 represents the width of the tire in millimeters;
● 65 is the ratio of height to width;
● H is the speed rating;
● R means radial; and
● 15 is the diameter of the wheel (in inches).

A "B" in place of the "R" would mean the tire is of belted bias-ply construction. A "D" in place of the "R" means diagonal bias construction.

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 "DOT" letters certify compliance with all applicable safety standards established by the Department of Transportation.

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.  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: tread wear, traction and temperature resistance.

SERVICE DESCRIPTION:  Some speed-rated tires carry a Service Description, instead of showing the speed symbol in the size designation.  The Service Description, 89H in this example, consists of the load index (89) and speed symbol (H).  The H in this case indicates the tire's maximum speed is 130 mph.  See the chart to the left for other speed ratings.

TREAD WEAR, TRACTION, and TEMPERATURE: The tread re 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.

NOTE:  It is incorrect to link tread wear grades with projected tire life.  The relative performance of tires depends upon the actual conditions of their use and may vary due to driving habits, service practices, climate, and road characteristics.

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.

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.

Typical information on a light-truck tire:

● LT" stands for Light Truck. "LT235/85R16" is the size designation for a metric light truck tire.

● LOAD RANGE D" identifies the load and inflation limits.

● RADIAL" indicates that the tire has a radial construction.

● MAX LOAD SINGLE 2623 lbs. AT 65 psi COLD" indicates the maximum load rating of the tire and corresponding minimum cold inflation pressure for that load when used as a single. For normal operation, follow pressure recommendations in owner's manual or on vehicle placard;

● MAX LOAD DUAL 2381 lbs. AT 65 psi COLD" indicates the maximum load rating of the tire and corresponding minimum cold inflation pressure when used in a dual configuration.  Other markings on the sidewall have the same meaning as described for the passenger car tire.

Inflation pressures are printed on a placard which is usually attached just inside the driver's door.  Pressures shown are recommended for a vehicle with original equipment tires.  Never exceed the maximum pressure ratings shown on the tire.