We just finished installing our custom I-Forged wheels on the GTO. The fronts are 18" x 8" with 245/40/18's and the rear are 19" x 10" with 295/35/19" Yokohama AVS Sports. Needless to say, the rear were not a bolt-on. A rolled fender lip, repositioned lower shock mount, notched A-arms, and modified inner fenderwells later, we bolted them into place. Installed on the car is a set of our prototype lowering springs. We should have these available in 6-8 weeks once we work through the correct rates and drop amount.