Tire sizes are simple to understand once you know how to read them. On this page you will find a detailed explanation of the P255/65R18 109S tire code.

255

This number indicates the tire has a width of 255 millimeters.

65

This number means that your tire has an aspect ratio of 65%. In other words, your tire's sidewall height (from the edge of the rim to the tire's tread) is 65% of the width. In this case, the sidewall height is 0 millimeters.

R

This letter indicates how your tire was constructed. Radial is the standard construction method for 99% of all tires sold today.

18

The tire size was designed to fit rims or wheels that are 18 inches in diameter.