Reading a Tire

Your Sidewall Says it All – All of the information you need to know about your tire can be found right on the side of the tire, called the sidewall. The abbreviations you may see on the tires are standardized across the tire industry and manufacturers are required to have information about these categories on every tire:

• Tire Type – identifies the proper use of the tire. For example, “P” would indicate a passenger car tire or “LT” would signify a tire for light truck use.
• Tire Width – the tire’s width from sidewall to sidewall measured in millimeters.
• Aspect Ratio – the ratio of the tire's cross-section height to its width.
• Construction –indicates how the layers of the tire were put together.
• “R” = Radial; the layers run radially across the tire.
• “B” = Bias: the layers run diagonally.
• Wheel Diameter – measures the width of the wheel from one end to the other.
• 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 – specifies the tire’s maximum service speed. It is very important to note that this rating relates only to tire speed capability and is NOT a recommendation to exceed legally posted speed limits. The most common tire speed rating symbols, maximum speeds and typical applications are shown below:

• DOT – indicates that the tire complies with all applicable safety standards established by the U.S. Department of Transportation (DOT). A tire identification or serial number — a combination of numbers and letters up to 12 digits— is next to DOT.
• UTQG – is the abbreviation for the Uniform Tire Quality Grading, a rating system developed by DOT.