The side of your tire—known as the sidewall—contains all of the information you need to know about your tire. Regardless of the manufacturer, all tires are required to show this information.
Tire Type defines the proper use of the tire. For example, the “P” on the tire shown in the photo to the right means that this is a passenger car tire. If the tire had an “LT” designation, the tire would be for a light truck.
Tire Width is the width of the tire measured in millimeters from sidewall to sidewall.
Aspect Ratio is the ratio of the height of the tire’s cross-section to its width. In our example photo, 65 means that the height is equal to 65 percent of the tire’s width.
Construction tells you how the layers of the tire were put together. The “R” stands for Radial, which means the layers run radially across the tire. A “B” stands for bias construction, which means that the layers run diagonally.
Wheel Diameter is the width of the wheel from one end to the other. The diameter of the wheel shown here is 15 inches.
Load Index indicates the maximum load in pounds that the tire can support when properly inflated. You’ll also find the maximum load elsewhere on the tire sidewall, both in pounds and kilograms.
Speed Rating tells you the maximum service speed for a tire. “H” means that the tire has a maximum service speed of 130 mph. This rating relates only to tire speed capability and is not a recommendation to exceed legally posted speed limits.
DOT means that the tire complies with all applicable safety standards established by the U.S. Department of Transportation (DOT). Next to this is a tire identification or serial number—a combination of numbers and letters up to 12 digits.
UTQG stands for Uniform Tire Quality Grading, a rating system developed by DOT.
Except for snow tires, the DOT requires the manufacturers to grade passenger car tires based on three performance factors: tread wear, traction, and temperature resistance.
More Than 100—Better
Less Than 100—Poorer
The tread wear 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 track as one graded 100. Your actual tire mileage depends upon the conditions of their use and might vary due to driving habits, service practices, differences in road characteristics and climate. Note: Tread wear grades are valid only for comparisons within a manufacturer’s product line. They aren’t valid for comparisons between manufacturers.
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.
The temperature grades represent 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 thus reduce tire life. Excessive temperatures can lead to tire failure. Federal law requires that all tires meet at least the minimal requirements of Grade C.
For more information on your car or truck tires, visit goodyeartires.com or rma.org.