16" on an '05?

If the rotors are the same size as the current GT's, you can use as small as 15's. If the rotors are 13", you have to use 17's.
I thought I read they changed the bolt pattern on the '05 wheels, if that's the case then they won't fit.
 
ryanrule said:
well the new stang uses different backspacing or sumthin dumb like that. rather stupid of them to change that

At a certain point you have to break with the past if you really want to improve the car. Yea it would have been nice if the old wheels still fit, but times change and cars do too.

The backspacing was changed for a reason. The larger back spacing allows the suspension arms to be longer which improves both ride and handling.