It has not been said, but I assume that any spacer used will be "hub centric", where the spacer is machined on the back side to fit precisely over the hub extension that fits into the center bore of the wheel, and the front side is correspondingly machined with a hub extension to accurately center the wheel on the hub. Probably a moot point if the spacer used is thinner than the hub extension, but to me you need that hub centering feature for safety. Without it you are putting all load on the studs.