[bbs350z]

doesnt it say on the wheels themselves?

 

[jds62f]

not as far as I can tell, but these aren't show wheels with shiny new stickers either. I think I answered my own question, the lotus hub requires a 56.6mm bore wheel and the bore of 4x100 ce28n appears to be 65mm. Nengun.com has some metal hub centric rings with this ID/OD

 

[richthom]

I got my from Hub Rings / Spigot rings 6,25 ? only - HubCentric-Rings.com
56.6-65.1 not metal, but very stiff

 

[jds62f]

hopefully this isn't premature (will edit if that turns out to be the case) but I ended up getting rings from rays. The stated size is 56.5mm / 65.0mm but the actual measurements given to my local rays dealer is 56.4mm/65.1mm. This matches what I've been able to measure off some hub centric spacers I already have (with no markings on them).

 

[ashanson]

Did those fit well? Mine didn't come with any, are they absolutely necessary?

 

[Aedo]

Did those fit well? Mine didn't come with any, are they absolutely necessary?

Yes

 

[jds62f]

so my actual ring measurements ended up being 64.85mm OD x 56.55mm ID. After thinking about it further I don't think that the rings are actually responsible for 'transmitting force to the hub' like some people say... all the rings I've found are either plastic or aluminum, which are easily deformed materials. If they were actually handling much load I think they would need to be made out of a much stronger material.

Having said that, I do think they are necessary to properly center the wheel on the hub, and they are necessary to make sure that the bore of the wheel is concentric to the bearing when you tighten the wheel down.