I'm in the same boat. 1.5" T-bar lift with 2" add-a-leaf in the rear. I was able to fit 31's fine (other than rubbing the frame) but when I went to the 265/70/17's I had to chop about 2" out of the back of the front fenderwell. I'm going to do some more trimming in both the front and the rear once things warm up in the summer. The 265/70/17 is approximately the same as a 32x11.5x15.

I'm pretty sure that some people are not understanding the differences between a ZR2 and a regular Blazer. Even setting aside the factory lift on the ZR2's, they also came with wider fender wells, and stiffer torsion bars which will likely sag a whole lot less over time than the soft squishy noodles that came one some regular Blazers. Mine came with the "Premium Soft Ride" noodle t-bars. Very soft and rode like a big 'ol Buick before I started moding things.