center bore regarding spacers

[godzilla200sx]

hey guys im after some 20mm bolt on spacers for the rear iv seen a couple of sets but there different center bore size one set is 66.1mm and the other is 73.1 , now i have rota slipstreams in 17" do i go of the centerbore of the wheel (were you might be able to help) or centerbore of the cars hub , im confused as to what to go for thanks.

[Evilchap]

Car centrebore, Nissan is 66.1 IIRC which I may not as I have the memory of a retarded fish, but either way go with the car CB then spigot ring on that to bring it up to the size of the wheel

[godzilla200sx]

Thanks buddy