The 17x8 doesn't clear the tie rod. The OEM Mustang rims that are 17x8 have a backspace of 5.72", and pretty much everyone I've seen run them has to add an 1/8" spacer to put the backspace at ~5.6" to clear the outer tie rod. A 17x9 with a +24mm offset has a backspace of 6". You'd need to get the backspacing to ~5.6" to get it to clear the tie rod, at which point you wouldn't be able to run 275's because of fender clearance, you'd be maxed out with a 255 and even that would be tight.
