Well I'll chime in here.. I have the 15x8 Rock Crawlers with 4" backspacing (read 0 offset) and 31x11.50R15LT TrXus STS on my X. Before the Torsion Bar adjustment and the 3pack AAL's I could not turn without serious rubbing (even with serious trimming) and offroading was out of the question. They didn't stuff into the wheel well enough. After the "Lift" things are much better however I still have not tried any serious compression. So make sure you do the math. The guys who make the custom backspaced Rock Crawlers said that I should look at a 4.75 backspace but I already had mine so.. maybe that's your answer??

One other suggestion is to keep the stock Steelies and put your new tire on that (although not the recommended size by Interco it will work)

Just my .02 and I had searched prior to my purchase and I didn't find the exact answer I was looking for either.

Hope it's somewhat helpful