ok here is what confuses me. according to this site
Wheel Specifications - Nissan 350Z & 370Z Wiki the my G35 wheels are 30mm
This is my car
The front wheels fits nice to me. its the rear g35 wheels that looks like its sunken in a half inch. so I defiantly need +15mm for my rears. but I dont know if +30mm 17x9 Battles will fit like 30mm 18x8 stock g35's. if it matters my g35 wheels have 245/45's in the front. so that could be why it doesnt look sunken, but it does rub like a bitch