How to Read a Tire Sidewall

When shopping for tires, you need to know what the numbers and letters on your sidewall mean to select the appropriate replacement tire for your ride.

The Basics of Tire Sidewalls

In addition to the tire's brand and line names (tire model), there is a lot of information provided by the manufacturer on the sidewalls of the tires they produce. Some of the branded information provides the tire's basic dimensions and identifies the week it was produced. Other branding lists the types of materials used internally to reinforce the rubber, along with the tire's maximum inflation pressures and loads. And others confirm the manufacturer certifies the tire meets various industry standards and measures up to the government regulations of the nations in which it will be used. Let's look at a "Bridgestone Potenza RE040 205/50VR15 85V" and what these markings mean.

Tire Brand

The brand, in this case, is Bridgestone. This is the company that manufactured the tire.

Tire Series

This is a Potenza series tire. Tire manufacturers often create a series of tires with somewhat similar handling and performance characteristics.

Tire Model

RE040 is a pretty accurate identification of the general performance characteristics of this tire, regardless of its size. Tires in the Potenza series may vary, but tires of the RE040 model have virtually identical construction, tread compound, design, and ride.

Tire Width

The width is 205. This number is the width of the tire in millimeters. This is the most important number to describe a tire's contact patch.

Aspect Ratio

50 is the height of the sidewall from the rim to the tread, expressed as a percentage of the tread width. Lower aspect ratio (shorter sidewall) provides better turn-in response than a higher aspect ratio, but at the expense of less break-away warning and a more jarring ride. In extreme cases, even exposing the wheels to potential bending and breaking damage from potholes and other surface irregularities.

Speed Rating

VR (V-rated radial) is the speed rating, and V identifies a speed rating above 149 mph. The R means the tire is a radial. Virtually every new tire is a radial unless you have a particular tire for a classic car or a racing car.

Load Rating

85V is the tire's load rating. 85 means the tire is rated for 1,135 pounds. Multiply this by the number of tires on the car, for a maximum safe loaded vehicle weight of 4,540 pounds (including people, luggage, a full tank of gas) The last V merely repeats the V speed rating.

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