You could easily fit 10" rims with the relocation kit.
Here's my set-up
Rims are American Racing Torq-Thrust
ARE-105MS7865B
ARE-105MS8965B
Dr Diff 1" relocation kit gives me about 0.75-1" clearance from tire to leaf spring and rim to quarter panel on each side.
17x8 (4.5" BS) up frt - 17/225/50 (25.9") $95 each
18x9 (6" BS) in rear - 18/275/40 (26.7") $115 each
I looked at the 285's for the rear but it was almost $100 more per tire. I looked for common sizes to keep the cost down.