I own a GT 500 and never liked the stock 18" Rims. I was very disappointed to find out the "Shelby" Rims made by American Racing do not fit a Shelby GT500. They fit regular Mustangs or regular Shelbys but not the GT 500 due to the oversized brakes on the front. Additionally you want a wider rim on the rear for a GT 500 and the Shelby Rims were not offered with the wider rear. I finally selected the 20" American Racing "Rogue" series due to the fact they come with the proper offsets so you dont need spacers and it also comes with a 10" wide rim for the rear. This car needs a wider rear rim because it burns rubber too easily with the 18 x 9's.
I know what you're talking about. I just put some recently released foose legend nitrous wheels on my 2007 gt 500. The fronts are 8.5 wide, and the rears are 10 inches wide, they have a very deep dish and being 20 inches tall they jump out at you. I am going to lower mine and then i will be set.