XXR 521's or something like that. its a shame they dont really fit mustangs that well because they look amazing!

They actually do fit our cars depending on what you consider a proper "fit". I personally think they look pretty damn good on the car.
http://www.stanceworks.com/forums/showthread.php?t=29963
Scroll through the thread and when he swapped the tires to a 275/35/20 they look even better. He's also on these forums too under the same name.
Stretched tires so they can compensate for improper offset is not proper fitment.
That's why I said whatever proper fitment is to you. Its different for everybody. You'll also notice later in that thread he swapped to a bigger tire and still had no rubbing issues. Its literally just personal preference.
You know I've followed his threads before when he was going through the 2011+ front end conversion but never noticed the wheels as something I liked lolThey actually do fit our cars depending on what you consider a proper "fit". I personally think they look pretty damn good on the car.
http://www.stanceworks.com/forums/showthread.php?t=29963
Scroll through the thread and when he swapped the tires to a 275/35/20 they look even better. He's also on these forums too under the same name.
these being a 25 offset, I imagine I'll get some rubbing then? the plan is to run 285/40/18's squareYou need offset in the 43 to 45 range for a 10" wheel to fit all four corners. If you just want to fit the rear you have a little more leeway to move the wheel inboard