For reference, I ran 225/45 RS3's on a 17x7.5 +45 stock without issues. I currently am roughly 1.5" lower on intrax springs and koni yellows and still am running that setup (note that I pinched up the inside front fender tab, and on hard transitions the tire has rubbed the paint off the inside edge of the front fenders)
2003 Twilight Blue ZX3
BBK, Quaife, Spec stg. 2+, Fidanza, and more...
2006 Pitch Black ST
Cold air intake (HID retrofit coming soon)