I know this should probably be in the Tire and wheel area but I posted over there and didn't get much response.

I am interested in getting just a little more sidewall to deal with some rough Texas roads. I want to keep the raked look of having the rear wheels 1 inch larger that than the front as in 17's and 18's inch wheels. I see that I can get a much larger selection of tires by switching to 225/45x17 and 255/40x18. The hard part seems to be finding 17 and 18 inch wheels in the right bolt pattern and offset. does anyone have any ideas for wheels or has anyone done this?