How to Read Tire Sizes

Tires are some of the most important components on your vehicle. They keep you safe with good traction, they keep you driving comfortably by cushioning bumps in the road, and they’re vital to keep you driving at all. That being said, which tire should you choose for your vehicle? The best way to find out is by reading your tire size code.

Want to learn how to read your tire size code? Just follow this guide our service team at Andy Mohr Volkswagen has written for Avon, Indianapolis, and Plainfield drivers today!

What Is a Tire Size Code?

Tires come in all different sizes and finding which tire size your car needs is important to make sure it fits on your vehicle. The way to find the tire size is simply to look at the tire size code on its sidewall.

A typical tire size code might look something like this: P245/45 ZR19 98W. It may seem like a jumble of numbers and letters, but each number and letter means something important about your tire, including its dimensions and even how it’s built.

How to Read Your Tire Size Code

So, how exactly do you read one of these codes? Let’s take you step by step through that code we used above.

Tire Class: Each tire is designed with a different purpose in mind, and the first letter in your tire code will tell what that purpose is. In most cases, the tires you’re most likely to encounter are P class tires. These are your common passenger car tires designed for your basic day-to-day driving.

Section Width: Next you’ll have the width of your tire. This is measured in millimeters and is the width of your tire from one sidewall to the other. The wider your tires, the more surface area they offer, making them better for cornering.

Aspect Ratio: A key part of your tire measurement is the aspect ratio. This is a measurement used to gauge the size of your sidewall. This number is a percentage that shows how much of your tire’s width consists of the sidewall.

Speed Rating: You may be surprised to find that not all tires are designed to reach the same max speed. Your speed rating tells the speed your tires are designed to reach. In general, passenger vehicles have tires with lower speed ratings than what you might find with a sports car fitted with performance tires.

Tire Construction: There are a lot of ways to build a tire and this letter will tell you what kind of architecture your tire uses.

Wheel Diameter: At this point, you should see a 2-digit number that shows your wheel diameter measured in inches.

Load Index: After that, you might see a second 2-digit number that indicates your tire’s load index. This is a gauge of how much weight your tires can handle. You should pay particular attention to this if you have a truck that carries large payloads.

Speed Rating: In some cases, you might see your speed rating in this location.