Back to all

What's in a Number? (What Tire Numbers Mean)

May 2, 2021

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.

Tuffy Clinton Township
19535 15 Mile Rd
Clinton Township, Michigan 48035
586-792-6660
http://www.tuffyclintontownship.com

More articles from Tuffy Clinton Township

Regular Schedule or Severe Service Schedule at Tuffy Clinton Township?

April 21, 2024

Today's Tuffy Clinton Township article focuses on severe service maintenance. Many Clinton Township drivers are not aware of them and yet there are also very vocal advocates in MI who think that severe service schedules apply to everyone. Somewhere between a complete lack of awareness and the di... More

Save Fuel by Watching Your Weight

April 14, 2024

Most Clinton Township drivers are all talking right now. Better gas mileage. Fewer emissions. MI folks want to save the environment and our pocketbooks.And we Clinton Township drivers all know or should know that preventive maintenance will help maintain maximum fuel efficiency. But is there so... More

How to Radiate Cool (Radiator Care)

April 7, 2024

There's nothing that radiates cool like a vehicle radiator that's helping to keep your engine running at the proper temperature. You don't have to baby it, but you can't simply ignore it, either. Let's take a quick dive under the hood to let you know what the radiator is doing. It takes the he... More