Back to all

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

November 15, 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.

Tuffy Tire & Auto Service Center Winter Springs
5225 Red Bug Lake Rd.
Winter Springs, Florida 32708
407-986-2325
http://www.tuffywintersprings.com

More articles from Tuffy Winter Springs

Make Your Battery Last

May 5, 2024

Today's report from Tuffy Tire & Auto Service Center Winter Springs is on vehicle batteries, why they die and what we can do to lengthen their life. Most of us have had a dead battery at one time or another. In fact, it would be very unusual if you hadn't. You may be surprised to learn that only ... More

The Tuffy Tire & Auto Service Center Winter Springs Guide to Saving Fuel: Car Weight

April 28, 2024

The team at Tuffy Tire & Auto Service Center Winter Springs in Winter Springs, and Florida car owners are all talking right now. Better gas mileage. Fewer emissions. Winter Springs drivers want to save the environment and their pocketbooks.And we all knowor should knowthat preventive maintenance... More

Clean Air for Your Engine: Engine Air Filters In Winter Springs

April 21, 2024

Every Winter Springs car owner who has taken their car in for an oil change has been told that their engine air filter's dirty. Here's what goes into the determination of when to change the filter: First, your vehicle owner's manual will have a recommendation of when the filter should be replace... More