Chevy tracker with bad tranny

[medictracker]

Ok it will be just me driving the tracker. Also this year does not have the LSD. I can tell you the passenger side rear wheel had a wheel seal go bad on it, or it is bad, so my guess is at one time the PO ran it with oil and either damaged the axle or the diff itself. Either way the whine that comes from the rear end sounds like a failing diff...While I never worked on the diff, i have had my fair share of replacing wheel seals, and anytime we did seal jobs, we flushed the axle and put new oil in it. but i think this sucker is bone stock and just has a crap ton of miles on it...BUT i figured i could just replace the spider gears with a drop in locker...

Whats the largest wheel size a guy can fit without having to cut the fenders?