Need help with wheel sizing.

Does anyone out there run a 275 tire on 17's underneath a stock fendered fox? I've seen it before, but don't have any idea what size wheels to use or the aspect ratio of the tire. I'll be changing the gear ratio anyways, so tire diameter isn't a big deal. I really want to know what rim width and offset to use so I don't have to roll the fender. Don't have any exhaust running over the rear axle to worry about either. Any and all accurate info is appreciated.
 
I run 275/40r17's on Maximuim Motorsports Koning rims. They're 17x9 w/ about a 6" backspacing, I'm not exactly sure what the offset is on them. I have some cobra rims that look to be about the same size but I haven't test fit them yet. I had to 'roll' my fenders and use a bit of a spacer on the back to clear the rear inner fender.