my '83 has a 2 inch body lift and i'm running 31 inch tires. they are skinny (215/85x16) and i'm having no problems at all. no clearance or rubbing issues even at full lock. wider tires might be more prone to rubbing, idk.
but even without the body lift, i had 235/75x15's on it with no problems. and just so you know, 235/75 and 30/9.5 tires are usually within 1/2 inch of being the same height.
just pulled out the original spare this past summer and discovered it was 195/75x15!
if you haven't already checked out all the u-joints, wheel bearings, hubs, etc. now would be the time to do it, when putting on new tires. my hubs are original and still working fine. when they do finally give out, i'll be replacing them with WARN hubs for the best quality. seem to be more problems with the other brands.
good luck and have fun with your '83!