#TechTip: Tire Sizes 101

Tire sizes can be confusing the first time you have to read them, so here’s a quick run-through:

What you'll see on the tire

This is a pretty standard example of what you’d find displayed on a sidewall. There are three measurements on most tires, and they refer to the following:

1. The width of the tire (in mm)
2. The sidewall height (displayed as a percentage of the width)
3. The type of tire and the wheel size

Example:

Here you can see the width is 245mm or a little over 9.5”.
The sidewall is 40% of 245mm wide, putting it at about 98mm on each sidewall
The “R” stands for Radial, and the 18 represents that the tire is for an 18” wheel

Common Misconceptions

“A certain sidewall size is always the same”: Wrong. Remember that the sidewall is a percentage of the width, so a 205/45 will have less sidewall than a 295/45.

“All tire widths are created equal”: Wrong. Different manufacturers have their own biases towards actual measurements. You may find certain brands run consistently narrower or wider than others. Sidewalls should be consistent, however.

What’s your tire size? Post it below!