I asked this question a while back, and Chaz from NAGTROC took me up on the question. Does an 18 inch wheel fit over a 390 mm 2012 Nissan GT-R rotor? The answer is affimative, as long as its the right wheel, and the wheel weights are placed at the back of the wheel not the front.
For more information on wheel and tire fitment, check out this thread.
|18 inch TE37 over a 390 mm rotor|
|TE37 Goodness for GT-R|
The two wheels we tested for clearance were Volk TE37s 18x9.5 +22 and Advan TCIIIs 18x10 +35. Both wheels cleared the calipers with about 3mm's worth on the TEs and 5mm's worth on the TCIIIs. The only thing you'd have to do to mount these is to make sure when you balance the wheel the weights are placed in the back or at least away from the calipers.
|18 inch Advan TCIII wheels over 390 mm rotors|
|Advan TCIII over a 2012 Nissan GT-R brake rotor|