What do the numbers on the sidewall mean?
The series of numbers and letters on your tire indicate the type of tire and the size. You commonly see a P for passengers, although LT for light trucks is also common. The number next to the P is the tire's width in millimeters. The next two numbers are the aspect ratio of the sidewall height to the width. Next, you'll see an R for radial, the construction used to make the tire. Rarely you'll see D for diagonal or B for belted, but these are specialty tires. Next is the rim size in inches. After that is the load rating; the larger the number (up to 125), the more load the tires can take. Finally, the speed rating is T, which is most common with a speed rating of up to 130 mph. Speed rating can vary from A being the lowest to Y being the highest.