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Passenger Tire Sidewall Information
Example: P215/65R15 89H
“P” means this is a Passenger car tire as opposed to a light truck tire. P-metric is the U.S. version of a metric tire-sizing system.

“215” is the section width of the tire in millimeters from sidewall to sidewall when fitted on the recommended rim.

“65” is the aspect ratio of the tire, the ratio of height to width. This particular tire's height is 65% of its width.

“R” indicates that this tire is built with Radial construction. Other types of construction are indicated by the letter “B” for Belted Bias construction, and the letter "D" for Diagonal Bias construction.

“15” is the diameter of the wheel in inches.

“89” is the load index. Different numbers correspond to different maximum loads. This particular tire has an industry-standard maximum load of 1,279 lbs.

“H” is the speed rating of the tire. This particular tire has an industry-standard maximum service speed of 130 mph. Some tires use an older European system that features the speed rating in the size description of the tire.

The letters “DOT” certify compliance with all applicable safety standards established by the U.S. Department of Transportation (DOT). Each tire also features a tire identification number consisting of up to 11 numbers and letters.

The sidewall also indicates the type of cord and number of plies used in the sidewall and under the tread.

Light Truck Tire Sidewall Information
Most of the markings on a light truck tire sidewall have the same meaning as those on passenger tire sidewalls. The following additional markings apply only to light truck tires.

“LT235/85R16” is the size designation for a metric light truck tire.

“LT” stands for Light Truck.

“LOAD RANGE D” identifies the load and inflation limits of the tire.

“MAX LOAD SINGLE 2623 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.

TIRE GRADE
Tire Grades: Uniform Tire Quality Grading System or UTQG
The Department of Transportation requires tire manufacturers to grade passenger car tires based on three performance factors: treadwear, traction and temperature resistance.

Treadwear
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 as one graded 100. Your actual tire mileage depends upon the conditions of use and may vary due to driving habits, service practices, differences in road characteristics and climate.

More Than 100 - Better
100 - Baseline
Less Than 100 - Poorer
Note: Treadwear grades are valid only for comparisons within a manufacturer's product line. They are not valid for comparisons between manufacturers.


Traction
Traction grades 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 traction grade is based upon "straight ahead" braking tests. It does not indicate cornering ability.

A - Best
B - Intermediate
C - Acceptable
Temperature
The temperature grade represents the tire's resistance to the generation of heat when tested under controlled conditions on a specified indoor laboratory test wheel. Sustained high temperatures can cause the materials of the tire to degenerate and reduce the life of the tire. Excessive temperatures can lead to tire failure. Federal law requires that all tires meet the minimal requirement of Grade C.

A - Best.
B - Intermediate
C - Acceptable
LOAD INDEX & SPEED RATING
While there is no industry-wide definition of Load Index, truck tires are frequently marked with a ply rating and equivalent Load Range. These markings are used to identify the load and inflation limits of that particular tire when used in a specific type of service.

Many tires are available in speed-rated versions to match the speed capabilities of the world’s fastest cars. Generally, it is recommended that a speed-rated tire be replaced with a tire having an equivalent or greater speed rating.

However, if you never drive at speeds near the limits of your speed rated tires, you may choose to replace them with tires having a lesser top speed rating.

In situations where tires having different top speed ratings are mixed on a vehicle, the maximum speed certification is limited to the top speed certification of the tire with the lowest speed rating.

Speed ratings do not indicate how well a tire handles or corners. They certify the tire’s ability to withstand high speed.