The wheels are one of the few automotive parts where a quick installation may dramatically alter its appearance. You can choose between bigger and smaller wheels, but 24 inch wheels are about as big as you can go if you want to make a significant impression. You'll need rubber for those large new rims, and they won't be cheap. Sizes 255/30-24, 285/40-24, 355/25-24, 285/30-24, 295/30-24, and 305/30-24 are suggested by Tire Rack. These sizes are typically only available in particular high-performance tires, and their prices reflect this. Consult your neighborhood tire shop for the proper size and installation costs.
