http://www.ezaccessory.com/Billet_Hu...es_p/5112m.htm

If you look at the photo, you can see a raised lip. This engages the inside diameter of the center hole in the wheel, forcing it to stay centered. "Hub" is what it uses as a reference and Centric" for what it does.

The center hole is a close fit on the hub-just like the wheel is.