Im new here and have a question....... I have recently cut the plastic off of the bottom of the bumpers on my Tracker. Just looked like they were made for a race car not for a 4X4 . I purchased the 2 inch body lift from RRO and will be putting them on when they arrive. I have also purchased the 2.5 inch backspaced wheels from wheelers . My question is this, If I go with 235 or 245/75/15 Destiny MT's from pep boys, will they rub on the suspension? I keep reading where quite a few people are having this problem with the bigger tires. Also how high in inches are 235/75/15 and 245/75/15 tires? Keep reading on here about 27,28, 29 inch, etc. without the tire size. Thanks!

Let me see if I get this right    :
235*0.75/25.4=6.93 (Distance from rim to tread in inches)
6.93*2+15=28.88" Diameter

245/75R15 are 29.5" in diameter

Quickly, 235 is the tyre width (can be slightly different to tread width), 75 is the ratio of tyre height to width and 15 is the rim diameter.

Or you can find a web site that does it for you, a google search gave:
http://www.miata.net/garage/tirecalc.html

And there are many others.  Feel free to correct me if any of that is wrong. 

I had Bridgestone Dueler M/Ts  on my '96 2-door, 235-75/15, stock alloy wheels (the 3-spoke ones).  Slight rubbing on the frame behind the front tires at full lock.  It's really more of a polishing than anything.  You get a nice shiny spot, but that's about it.  Later, I put on 1" or so spring spacers which alleviated it a little, but not completely. 

Seriously, though, it's nothing.  If you don't have big side lugs on your tires, you might not even notice.  Although, I suppose if you run chains in the winter it could be a bit annoying.

Here's a pretty cool tire size calculator page:

http://www.powerdog.com/tiresize.cgi

You can put in different sizes and get the size difference calculated, along with percentages and how the speedo is affected.

Be sure to check specs on the specific tire brand/model if you can.  A certain Bridgestone 235 70 might be up to 1/3 of an inch bigger or smaller than, say, a Dunlop or BF Goodrich in the same size.  They all run a little different.  Of course tread depth and section width play a role too.

Dave

i like this calculator, it's so easy to use that i figured it out

http://www.1010tires.com/TireSizeCalculator.asp

but the one you refers to is probably better