I have 18" wheels and stock is 265/60/18 and I am going to get Firestone Destination A/T and can get 255/70/18.

Will I have to trim or level/lift?

How accurate are the speeds as well?

here is the link to the dimensions:

http://www.discounttiredirect.com/di...foTireMath.jsp

 

Well, crap, it takes the numbers out.

Roughly 1.5 in increase in total diameter and 0.75 in increase in sidewall height. Speed at 65 = 68 and at 75 = 78.77

So, does this mean 2 1/4" total with 1 1/8" moving toward the fender well and mud flap and suspension, on each "side" of the tire?

 

Close. A .75" increase in sidewall height will naturally lead to a 1.5" total diameter increase. So the answer is no, there will be .75" "toward the fender well" and .75" "toward the mud flap".

Given your specs, you are actually going to a "skinnier" tire (255 vs 265). Although your diameter is going from 30.51in to 32.05in.

I think there are plenty of people on this board running a 32" tire but they have the 2" leveling kit. It's just as much the width of the tire as it is the height. In this case you don't need to worry about width, just height (if you stick with 255's)

hope that helps.

 

You have to be 'leveled' and you may still have to trim some. 32" is a big tire for our trucks, could be trouble. And yeah, the speedo will definitely be off.

I wouldn't do it.

 

I have a 2inch leveling kit and a 31.7ish tall tire and I still get occasional rubbing. Without a level you will definitely run into issues.