How to Interpret Those Tire Numbers

Increase Your Tire Knowledge

There are many different kinds of tire varieties like compacted, full Size, limited-use, all-terrain, mud-terrain are just some. Some tires have limited tread life and are to be used for a temporary emergency. These are usually what we used to call donut tires. They are a lot smaller. 

How do you know what kind tire came stock with your vehicle? There is a placard in your vehicle. It is usually located in the driver's side door opening. re smaller, we know them as donuts. But you can also tell by looking at the placard in your vehicle.  

My front, rear and spare are all the same -- lt255/75R17 C 

What do those numbers mean?  Good Year Tire Size Help

The first letter or letters are the type -- lt = light truck

The first set of numbers is the tire width from sidewall to sidewall -- 255 mm 

The second set of numbers is the aspect ratio  -- 75 means the height is equal to 75% the tire's width. The bigger the aspect ratio the bigger the sidewalls. 

The next letter "R" stands for Radial. The construction of the tire which means the layers run radially across the tire.

The next number, 17, is the wheel size. 

Now don't confuse tire and wheel.  Tires are the rubber part that grips the road... the wheels are the round steel or alloy part the rubber tire goes on. 

There are also a lot of other markings on your tires check this page out for more information.  TireRack.com 

My tires are made in the USA and are for the mud and snow. They are tri-guard 3 ply sidewall Mud-terrain T/A.

Then there is the 111/108 Q. This has something to do with the load index and I am not sure what the Q stands for.  

They have Load Range of C which has to do with how much weight they carry. The C's are lighter and a better ride than D & E .