I'm not even 100% sure I'm going to lift my truck to fit bigger tires, but just for farts and giggles I've been looking online at different tires. But I don't really understand all the numbers associated with size and such.

For example, I have an '89 Blazer S10 4x4 I was planning on doing a 3" body lift from LMC and fitting 31's, but then I keep hearing about all these problems with it like rubbing issues, and I saw someone say that with the body lift, the fan shroud lifts up too and causes cooling issues. So anyways, I was looking to see if I could fit just a bit bigger tires even if I have to trim a little. And I don't want to do a T-bar crank because I've heard on here about front end components wearing out quicker.

Sorry for the long post, my main questions are:
1. How do you "read" tire sizes
2. How serious are the problems I just stated about the body lift or T-bar crank?

 

in the stickies (2 threads above yours) is this thread which should help --> it will link you to this which has a bunch of info

or skip all that and use this idiots guide (thats how i roll) as it has neato pictures and is fairly helpful
this is what i would click

hope that helps

 

Thanks, it KINDA helps, but I still don't fully understand it.
So, let's take for example my tires, 215/75/15
The 215 is the width? As in from one tire wall to the other? This confused me because I always thought the first number had to do with the height of the tire.
And just to cover all my bases, the 75 means that the height is 75% of the 215? Which would be just over 161cm. And that's gotta be from the lip of the rim to the outer edge right?
And I know the 15 is the rim size.

But what about on truck tires, say 31x10.5/15.
In this case, the 31 is the height of the tires in inches from the ground? and the 10.5 is the width right?

 

the 215 is the diameter of the tire. depending on the brand of the tire there are differences between 215s. The 75 represents the width of your tires. 75 is pretty skinny, 70s would be wider and so on and so forth. tires such as 31x10.5x15 is an actual measured size so the diameter of the tire is 31 inches and the width is 10.5 inches. if you don't want to go through the hassle of putting a lift on you can either go to 235/75/15 or 235/70/15 or 30x9.5x15. These are all around the same size the 30s are probably going to be the tallest in most brands and then the 235/75/15s. 235s are anywhere from 29 inches - about 30 inches depending on brand. The bf Goodrich i used to have were about 29.5". You might have issues rubbing with your blazer I'm not completely sure what the differences are in the older blazers. I have 31's on my blazer with a t-bar crank and shackles and they still rub a little bit. Hope this gives you a better idea

 

Ok now I'm confused .
In the link ABN gave me, from Uniroyal Tires, it said that the first number is the width, and the second number is the aspect ratio of height in relation to width.

There's no way the 75 could be the width of the tire, because 75mm is only 2.9 inches.

And isn't the diameter of the tire the rim size?

 

The first number is the width... you were correct... benedict missunderstood....

so say you have 235/75/15 or 235/75r15

same tire....

235 is the width of said tire
75 is the height as you stated (diameter)
15 and r15 is the rim size diameter for said tire

 

I'm confused at the confusion.
Read this page at discounttire.com for a very clear explanation of tire sizing.

 

I'm with him ^^^, but i can't believe how slick that link is...
that link seasame streets it down for you. *links to favorites*

 

My tyres (Bridgestone Dualers A/T) are LT235x75 r15 6pr (Only 15" size tyre available here for these trucks - no 235x70's).

They measure from ground to top of tyre at 710mm (28") give or take at 36 psi.

I've had to trim a wee bit in front of the doors at the bottom to clear for turning.

When I drive through a ditch the top of the tyre hits the fender. At this time there is a fair amount of wear evident on the fender flare but not the tyre.

However, when the tyre eventually wears through the fender flare (which is a strong plastic), I'm sure I'll have issues with the tyre vs fender so I'll need to do a lift of sorts. Of course, as the tyre wears this may not become an issue but I do still want to do a t-bar crank of 1" (not keen on the increased suspension parts wear issue going higher - so I figure 1" will be safe).

Then I'll need to lift the rear. I've not seen a 1" shackle kit so I may need to fab some locally.

If I need more lift I may consider a 1" body lift.

 

Ah, thank you! I totally understand now . Sorry for the noobiness and confusion haha. Sad part is, I actually worked at a junkyard in the tire department for a while, but all I had to do was stick a blade in bad tires and take them off the rim.