What's in a Number? (What Tire Numbers Mean)
August 9, 2020
You've probably never paid much attention to the writing on the sides of your tires, but they contain a wealth of information. There's a long combination of letters and numbers that can tell you a whole lot about what tires your vehicle was designed to be riding on. Let's check out this example found on an SUV: P245/70R17 108T.
The first letter, P, means it's intended for passenger vehicles. If there's no letter, it means it's a metric tire. If there's an LT at the beginning or end that means a tire designed for light trucks.
Moving on to our example, the 245 shows how wide the tire is in millimeters from sidewall to sidewall. The number that follows in our example, 70, means the height of the tire is 70% of its width. The letter after that in our example, R, describes the type of tire (on this vehicle, radial). Following that is the diameter in inches, in our SUV example, 17 inches.
How much load the tires' sidewalls are designed to take is what that next number is all about (108 in our example). The higher the load index, the more weight the sidewalls can take. And the last letter is the speed rating of the tire, in our example, T. The further along in the alphabet that letter is, the higher its speed rating. So now you know what those letters and numbers mean. But why are they important?
When you are getting ready to replace those tires, those numbers are telling you what the original equipment was when your vehicle was new. Sticking with the same rated tires is always a good idea. If you don't know what you're doing, trying different sized tires and wheels can cause real issues when it comes to performance and safety, considering all the computerized systems now found on vehicles. When in doubt, consult your service advisor when it comes to buying new tires. He or she knows what those tire numbers and letters mean… and a whole lot more.
Charlie's Fast Lube Dexter
414 N 1 Mile Rd.
Dexter, Missouri 63841
573-614-7886
https://charliesfastlubedexter.com
Need Service?
More articles from Charlie's Fast Lube Dexter
Fuel Saving Tip: Slow Down in Dexter
March 9, 2025
Theres not much Dexter drivers can do about the price of gas in Missouri, but we can control - up to a point - how much we use. Our driving habits can dramatically affect our fuel economy.The first thing we can do is watch the go-pedal. Hard acceleration just sucks the gas. Gently leave stop ligh... More
Plugging Away (Spark Plug Replacement)
March 2, 2025
If you drive a vehicle with a gasoline engine, thank the spark plugs for igniting the gasoline/air mixture in each cylinder that keeps your vehicle traveling smoothly down the road every day. Your spark plugs work hard, firing thousands of times in a well-choreographed order, and you usually don... More
Chilly Warning (Diagnosing a Noise in Cold Vehicle)
February 23, 2025
When the weather gets colder, sometimes the noises your vehicle makes will change. For example, you may notice a whining sound when you get going in the morning. It may go away when the vehicle warms up, but it's best not to ignore that sound because it could be a warning of worse things to com... More