The wheels I ordered (konig rewinds 15 x 7 0 offset) came with black rings. I think they are centering rings. They will not fit over the very last lip of the hub. I grinded down the plastic tab on the center cap of the wheel and smashed down the grease cover, the wheels now fit great. My concern is not having that black ring on. Does it matter?

I will take a stab at this. I have 14x7 Konig Rewinds on my car. Datsun Zs are lug-centric, not hub-centric. You don't need centering rings on the hub. I would double check with the business you bought the wheels from.

I think the rewinds use acorn style lug nuts, which will center the wheel.

Thank you everybody. The car is all most done! We never could have done it without Classic Zcar Club! You guys rock!!!