17's look awesome on S15's as the 15 is a little smaller. My S15 has 18x10 et22 back ET 18 Front, with 255/35/18 and 225/45/18. I have a moderate stretch on 10j so 9.5j should sit just right.
Man I am talking into buying these for me! Although my Blitz technospeed are my best wheels of all time.