Back to all

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

November 10, 2024

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 Jackson
1901 E. Jackson Blvd.
Jackson, Missouri 63755
575-243-2226
http://www.charliesfastlubejackson.com

Need Service?

Request a Quote

More articles from Charlie's Fast Lube Jackson

Beware of Potholes! (Avoiding Pothole Damage)

November 3, 2024

You may live in a region where roads become pockmarked with craters known better as potholes. They're caused by moisture seeping through a compromised road surface that can freeze, expand and literally punch holes in the road. And when your vehicle hits one of those holes that's big enough, the... More

Clean Slate (Protecting Vehicle's Finish)

October 27, 2024

Winter is one of the hardest times to keep your vehicle clean. But did you know neglecting to wash your vehicle in winter could cost you a significant amount of money in the long run? Here's why. Many areas deal with snow and ice in the winter, and the salt and sand that are used to keep the road... More

Unlock the Secret (Malfunctioning Door Lock Actuator)

October 20, 2024

What a convenience power door locks are on a vehicle. The latest don't even require you to push the button on the key fob; all you have to do is have it with you. But sometimes there's a component of power door locks that can fail, especially when they are used several times each day. Those ar... More