What's in a Number? (What Tire Numbers Mean)
May 17, 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 Pro Troy
512 East Maple Rd.
Troy, Michigan 48083
248-270-3002
Need Service?
More articles from Auto Pro Troy Auto Repair
Taking the Heat (Batteries in Hot Weather)
January 19, 2025
Quick question. Which is tougher on a vehicle's battery, the heat or the cold? Believe it or not, it's the heat. Think about it. The battery often sits in the engine compartment next to that motor generating lots of heat. That can accelerate corrosion in the battery and may even cause water i... More
Breathe New Life into Your Engine (MAF sensor replacement)
January 12, 2025
If youve noticed your vehicle is hard to start, stalling, or has lost power, the culprit may be a part with an odd name: the MAF sensor. You may have never even heard of a MAF sensor, but its important that it be working correctly, or you may be experiencing some fairly significant engine issues... More
Keeping Yourself in Suspension (Control Arm Assembly Replacement)
January 5, 2025
When you are pointing your vehicle straight down the street, it should go straight. Thats pretty straightforward, right? Sometimes, though, you may notice you have to keep adjusting the steering wheel to keep going straight. While that could be caused by many different issues, one possibility i... More