I believe one route folks go is to take advantage of the Viper tire sizes, as they are somewhat common. 275/35-18's front and 335/30-18's rear.
I'm 100% with Aurora40. I have 10" and 12" X 18" and John from CCW gave me a custom offset after I took some measurements and they fit perfectly, tucked and no rubbing; love the ride, look and traction.