depends if what diff you got or if its tubed.
normal diff i would say 8inch rim with around 235 tyre
with a 10 bolt diff you can fit a 255 tyre easy and you can get 265/275 tyre to fit so around 9/10 inch rim
yeh im gettin my vk tubbed cos i wanna put my standard 15 back on with a 265 275 wide rear tyre
On the front i run 8in with 235/45 and any wider they wouldnt fit as you cant even fit your finger in the gap between the front strut and the tyre.