How can I find out my tire size?
When it comes to tires, size really does matter. That's why it's important to know how to find your tire size. Here are a few tips to help you get started.
The graphic and data below will show you how to interpret tire size, understand it, and use it. If you decide to replace a new size or type of tire, seek advice from an authorized tire dealer because many optional tire sizes may have different load capacities and require wheels of a different rim width or diameter, as well as varying inflation pressure.
All passenger car tires in North America are sized using the metric system. This means that the tire size is expressed in millimeters (mm), and includes the width, height, and diameter of the tire. For example, a common passenger car tire might be sized as 205/55 R16 91V. Here's what each part of that size designation means:
205 - This is the width of the tire in millimeters (mm), measured from sidewall to sidewall. In this case, the width is 205 mm.
55 - This number is known as the aspect ratio and it expresses the height of the tire's sidewall as a percentage of the width. In this example, the sidewall is 55% as high as the tire is wide, or 110 mm (55% of 205 mm).
R - The "R" in this size designation stands for "radial," which is the type of tire construction most passenger car tires have today.
16 - This is the diameter of the wheel rim, expressed in inches. In this example, the tire is designed to fit a 16-inch wheel rim.
91 - The two-digit number following the "R" is the load index. It corresponds to the maximum weight that the tire can support when properly inflated. In this example, 91 equals 1,389 pounds (634 kg).
V - The speed rating is the final letter in the size designation and it corresponds to the maximum speed at which the tire can carry a load under ideal conditions. In this example, "V" equals 149 mph (240 km/h).
The width of a tire is measured in millimeters (mm), and corresponds to the distance between the widest points on each side of the tire. The width will be listed first in the size designation, followed by the aspect ratio (height).
Now that you know how to read a tire size, you can be sure to get the right size when it's time to replace your tires. Keep in mind that many optional tire sizes may have different load capacities and require wheels of a different rim width or diameter, as well as varying inflation pressure. When in doubt, seek advice from an authorized tire dealer.