And TIRES like 68Cuda said. 17" because you can't get good 15" tires anymore. And if you ever what big brakes they will fit. And got at least 8" wide rim. Preferably 17x9 with 275/40/17 ALL the way around. Some body styles won't allow that. Head towards 17x8or9 Mustang rims/tires on Craiglist/Ebay.
If you can afford that just run some 15x7 cop rims and some 225/60/15 tires with a high speed rating. That's what I did.