These were in another thread... 20X9s up front, 20X10.5s in the back. I don't know what tire size, but it's said to take no modifications to fit these.
I also plan to fix the tire problem on my 2005 when I get one.
I absolutely hate the stock tire wheel combo (235/50/17 all season pirellis) and since I live in a warm area I can ditch the skinny tall all seasons and get some decent meats and lower it a bit. I dont know about going larger than 18's though. The larger wheels and tires actually hurt your performance plus they cost too much and can look a bit ghette although there are exceptions. I figure on a 275/40/17 rear and a 255/40/17 front, perhaps 18's though.
So no 315s out back on the 05s???And the axle looks further in than other 05 GTs, their axles look to be pretty far out so I dont think deep dish will work.The stock tires are almost flush with the outer lip as it is, basically your only option is to put more tire UNDER the car, not out like the 99-04s which have alot of room for the tire to go out as well as in.