Reading your sidewall

The sidewall of your tire contains a great deal of information. The letters and numbers found on the side of your tire provide dimensions and performance standards that allow you to accurately compare tires. This list will help you understand the numbers and letters on your sidewall.

Example: P215/65R15 95H M+S

P (service description) identifies the tire as a passenger tire in the U.S. (P-metric) system of tire sizing. Other service descriptions include “LT” for light truck or “T” for temporary, which is generally used for small spare tires.

215 (tire section width) is the measurement of the tire, in millimeters, from one sidewall edge to the other sidewall edge. In general, the larger this number is, the wider a tire will be.

65 (aspect ratio) refers to a tire’s section height compared to its section width. An aspect ratio of 65 means that the tire’s section height is 65 percent of the tire’s section width. An aspect ratio is helpful in determining a tire’s purpose. Aspect ratios of 55 and below mean a short sidewall, which contributes to better overall handling and an improved steering response.

R (radial construction) is the industry standard for passenger tires. Radial tires are of a better construction with reduced rolling friction and improved fuel economy as compared to their predecessor, bias-ply tires. Bias-ply tires, which are marked by a “B,” are still used for some truck applications.

15 (rim diameter) is generally measured in inches. Tires are sized to a certain rim diameter. If you purchase a new set of wheels, you’ll need tires that match the diameter.

95 (load index) indicates how much weight a tire can support. A load index chart can provide information on the carrying capacity per tire for each load index number. For U.S. passenger tires, the load limit is listed in pounds on the chart. The original load index is listed in the owner’s manual or on the driver-side doorjamb. Replacement tires should not have a lower load index than the original number.

H (speed rating) represents the maximum tire speed at which a tire is designed to perform for extended periods of time.

Speed ratings do not apply to damaged, underinflated, overloaded or altered tires. Also, please note that tire manufacturers do not recommend exceeding speed limits.

Additional information on your tire sidewall includes:

Conditions:
These include symbols and labels that tire manufacturers place on a tire. For example, a snowflake and mountain symbol means that a tire meets or exceeds snow tire designation specifications while the “M+S” label is used on an all-season tire.

DOT code:
The DOT code is used by the Department of Transportation to help track tire production in case of a recall. The first two characters after “DOT” note the tire’s manufacturer, while the following two characters tell where the tire was made. At the end of the DOT code is a three- or four-digit number that provides the date of the tire’s manufacture with the first two digits giving the week number and the last digit or two giving the year. 

Maximum load:
This number indicates the maximum amount of weight that a tire can support when cold.

Maximum pressure:
This number refers to the maximum inflation pressure of the tire. The maximum pressure number is not the recommended tire pressure, which is noted in the vehicle’s owner manual and doorjamb. It is important to never exceed the maximum pressure or load, which can result in tire explosion and injuries or fatalities.

Treadwear rating:
This indicates the tire’s durability; the higher the number, the longer the tire’s tread should last. Projected treadwear is not determined by a government or industry standard, but rather each tire manufacturer by conducting independent tests. Road conditions, climate, tire maintenance and driving habits play a role in determining actual treadwear.

Traction rating:
A tire’s traction rating describes its ability to stop on wet surfaces such as pavement or concrete. Traction rating tests are performed during straight-line braking. Ratings are AA (best traction performance), A, B and C.

Temperature rating:
The temperature rating identifies a tire’s ability to withstand heat under normal operating conditions at recommended pressure. Temperature grades range from A, the highest and most resistant to heat generation, to C.

For assistance in selecting a replacement tire, call or visit Lehigh Tire.