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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 usefull.

Typical sidewall

P215/65R15 89H

Shown here is the sidewall of a popular "P-metric," speed-rated auto tire.

  • "P" stands for passenger,
  • "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.

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 below for other speed ratings:

speed rating chart

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A "B" in place of the "R" would mean the tire is of belted bias 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 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.

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 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.

It is wrong to link treadwear grades with your projected tire mileage. The relative performance of tires depends upon the actual conditions of their use and may vary due to driving habits, service practices, differences in road characteristics and climate.

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.

Some typical information on the sidewall of a light truck tire:

Tire inflation pressures are printed on a placard attached inside the driver's door. These pressures are the recommended pressures for your vehicle with original equipment tires. Never exceed the maximum pressure ratings listed on the tire.

Determining the age You can tell the week and year a tire was manufactured by looking on the inner ring, right where the rubber meets the wheel. There will be the letters "DOT" followed by a bunch of numbers and letters. The last four numbers give the week and year the tire was made.

For example the 12 character series concluding with the numbers 1502, would mean the tire was made in the 15th week of 2002.

When tires should be replaced based on age varies with who you listen to. But Ford and DaimlerChrysler recommend that tires be replaced after six years, regardless of their mileage.

If you have any questions or comments on this article, please email us.

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