Firstly, why oh why convert a 9000 series GT5 to a Group 4! The factory GT5 is a rare car, likely as few made as GT5-S!
I run aftermarket 17" rims on my factory GT5, apart from the diameter they follow the specs of the GT5/5S 10 spoke Campi's for width and backspacing with 13" rears and 10" up front. Tires are Michelin Pilot Sports 335/35 rear and 275/40 up front. IMO they work great, fill the flares as they should. They are higher profile than OEM tires, so cause the car to sit higher, I have the suspension set as low as I can go and as a result have some cracking on the front flares from tire rub.
