What's in a Number? (What Tire Numbers Mean)
November 13, 2022
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.
Auto Lab Livonia
36251 Five Miles Rd
Livonia, MI 48154
734-432-6000
http://www.autolablivonia.com
Need Service?
More articles from Auto Lab Livonia
Straight to the Point (Alignment Signs of Problems)
January 19, 2025
Its just common sense that your vehicle will drive better if all the wheels are lined up with each other and the road the way the engineers intended. When theyre not, that is called being out of alignment. Here are some signs that your alignment has problems. Your steering wheel isnt straight... More
Auto Lab Livonia Advice: Don't Overlook These 10 Automotive Services
January 12, 2025
Organization is the key to managing a busy life in MI. So setting up an annual calendar for vehicle care can keep Livonia residents on top of preventive maintenance. But you can't just write oil change every few months on the calendar. Modern vehicles have many systems that are vital to the safe ... More
Don't Blow a Gasket! (Valve Cover Gasket Replacement)
January 5, 2025
When you head out to your vehicle after it's been parked and notice oil leaking underneath it, that's something to have looked at right away. Oil leaks mean your oil level is probably low and running a vehicle in that condition can lead to expensive repairs. While there are many reasons oil leak... More