Tire Knowledge

I found a couple of free minutes the other day to get back to reading my Jeep Wrangler manual. Yes, I'm still reading it. My mom life gets pretty hectic sometimes with sports, scouts, school, summer vacations and all those other mom things we do. You know eat Bon Bons and watch soap operas. ;-)

I am at the section in the manual on spare tires. Who knew there could be so many different varieties -- Compacted, Full Size, Limited-Use. The manual states these tires should only be used for a temporary emergency. These tires have a limited tread life.


But how do you know what kind of spare tire your tire is? Some you can tell just by looking at them. They are smaller, we know them as donuts. But you can also tell by looking at the placard in your vehicle.  

I checked my placard on the driver's side door opening like the manual stated and it looks the the front, rear and spare are all the same -- lt255/75R17 C 

So I am guessing I am good to go. 


But what does that number mean.  Good Year Tire Size Help

Basically 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 

I know 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... But I'm not sure what the T/A stands for. 

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 I am told. 

Well, it looks like I may need to do a little more research on my tires. 

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