What's in a Number? (What Tire Numbers Mean)
December 27, 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.
Top Tech Auto Repair Royal Oak
3110 Rochester Rd
Royal Oak, Michigan 48073
248-585-0980
http://www.toptechautorepairroyaloak.com
Need Service?
More articles from Top Tech Auto Repair Royal Oak
Don't Neglect Your Spare (Spare Tire Care)
October 12, 2025
If you've ever had a flat tire, then you know welcome it is to have a spare tire that is properly inflated, in good shape and easy to get to. Problem is many of us don't even give our spare tire (if we even have one) a second thought. If you have an SUV or truck with a spare, it may be mounted o... More
Steer Clear (Power Steering Pump Replacement)
October 5, 2025
When it comes to ease and precision of steering, todays vehicles are engineering marvels. One of the keys to just how good steering is lies in the refinement of power-assisted steering which we know simply as power steering. At the heart of the system is an electrically or belt-driven power ste... More
Sounds Exhausting! (Exhaust Service)
September 28, 2025
Most of us know a bad muffler when we hear it. That loud, rumbling sound is unmistakable. Did you also know you can get a ticket for driving around with a loud exhaust system? If your exhaust system has a leak in it, it may be allowing poisonous gases inside your vehicle and could make you serio... More