I just put a set or 31 mt/r's on a 91 s10 blazer 3 days ago, he has a 3in body and it looks like it will still hit a bit with some large flex, but it shouldn't be too bad. I would go for 31's and no bigger just to be safe. good luck, try the mt/r it'll be totally worth your while.
I work at fountain obviously as i boast the mt/r to everyone, but testing has proven it to be good, and if you can wait till april there's a rebate of $25 a tire, sounds like nothing, but a $100 adds up.
It's notugly, it's a beautiful work in progress, and yes the rust is supposed to be there!
If your torsion-bars are in good shape 31 X 10.5 will fit. If you crank the t-bars up a bit you can gain an inch or two. If you cut out the fenders it is possible to fit 33's. A friend of mine is putting 33 x 9.5 on his blazer. It has 3" bodylift, t-bar crank, bushwhacker cut-out flares and springover in the rear. I am going to be running 36 x15.5 on my s-15 but it has a solid front axle. check out-