16x8 @ 4.25" will stick out past the cladding to a degree that will be easily visible and technically illegal in some states (but will look cool). Your pivot radius would be large enough for a 30" tire to possibly hit the front fender cladding on turns. If you're going with 16x8 rims, why not use a more common backspacing like 4 5/8" or 5"??