From what I've seen a +25/+30 is flush on these cars. DO NOT expect 17s to look good though, my car came stock with 16s and 17s just barely look okay. I'd say for track 18s would be the smallest thing you'd want to run and for street a 19 is probably the best fit for the wheel wells. I want to see one of these cars with the 350z rays 18" track rims to get an idea of fitment. When cars come with 18s stock 17s shouldnt even cross your mind as an option IMOI'm curious to see offset and wheel sizes for the genesis to. I'm thinking 17s are large enough 17x8 front 17x9.5 on the rear.