Following The type of service letter(s) is a three digit number that states the tire's sectional with (or cross section) in millimeters. Tire section width on Tire sidewallThis is the widest point of the tire's outer sidewall to the widest point of the inner sidewall. In this example the width is 195mm. The measurements are when the tire is mounted on a wheel of the proper size and inflated. (Convert millimeters to inches by dividing by 25.4)


Following the three digit Section Width is a two digit number indicating the aspect ratio of the tire. tire aspect ratio on tire sidewall
This indicates the tire's sidewall height from rim to tread as a percentage of the section width. The higher the number the taller the tire sidewall. This tire width is 60 percent of the side wall height.

R - Typically following the sidewall aspect ratio is the letter "R" indicating that the internal construction of the tire is of a radial design.
Tire sidewall information R radial
Nearly all tires in highway use today are radial. Non radial tires are of "Bias ply" and are indicated by the absence of "R" coding. Bias Ply tires typically do not perform as well as radials. Many bias ply tires sold today are used on historically "correct" vehicles that are not in daily use.

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Before you replace the tires on your car, minivan or truck understand the tire information code.

You will avoid being sold more tire than you need, and more importantly can avoid buying less tire than you need, which can be dangerous.