Wheel spacers will definitely be fine in the rear, if you want to fill the fronts, a set of 9" wide wheels with ~6" backspacing does it handily. I'm running 17x9 BBSs up front on the Cobra with 275/40s, they sit just outside the fender line (I'm sure that's technically illegal) and I barely rub on the swaybar and k-member. With 255/40s, I'm pretty sure I'd totally eliminate the rub while still filling the fender width.
