Optimum front size is a 17x8 with a 4.75 backspace. Since the front is stock, a 235/50R17 is probably the largest you can fit. If you do the Gulstrand Mod or taller balljoints or taller spindles to allow a negative camber curve, then a 245/45R17 should fit without rubbing.

On the rear you can do a 17/9.5 with a 5.5 backspacing. A 255/45R17 will definitely fit. The 275/40R17 typically fits, but can require rolling the fender lip in some cases (original manufacturing tolerances vary, and amount lowered may affect it).