Did a wheel fitment test last weekend. These are Foose wheels from my father-in-law's Roadrunner. These aren't the wheels I want, but they sure do dress up the car and get me excited about the wheels I do want. They are 17x9 with 235 40 17 Goodyear. I'm not sure what the backspacing is. The point of the exercise was to see what would fit and what offset I wanted.
The fronts fit great and filled the fenders well but the rear need to come out about an inch. I've decided that I'm going to go with a 17x9 front and an 18x9.5 rear. Still need to work out what the offset will be when I have the $$ to purchase.
235 is awfully narrow for a 9" wide rim. I run 275/40/17's on my 17x9's (front and back). And short, a 235/40/17 is only 24.5" tall.
As far as offset, you'll want pretty close to 0 offset with a 17x9". That's what I have on mine, 0 offset, or 5" backspace. A little more would be good, I think 5.125" backspace is absolutely ideal. At most 5.25" backspace, which is a 5mm offset. But any more than that and you'll hit the tie rod ends with a 17" rim.
In the back, you'll probably still want about 0 offset on an 18x9.5, which is 5.3" backspace. That will put you right up on the stock springs, you might need to run a small spacer. But much less than that and you'll be into the quarter with the tire. A 275/40/18 (or 17) is about as big as you'll be able to go without at least offset hangers, like Dr. Diff's 1" offset kit.
