these fit great with no spacer I have mocked these wheels up on my bravada which now has reg. c5 wheels on it. the only reason you would need a spacer is to get the rear wheels to sit out to ultra flush. its pretty hard to notice the back wheels sitting in a 1/2 further than perfect but each there own. I should bolt these up on the rear of the sy and take a pic to show no spacer and that way people can be a little more enticed!