Are hub centric rings mandatory?
 

Does this middle ring exist or should I cut it like the right one?

https://i.imgur.com/oYOMRji.jpg

I've found that a 5mm spacer will only give I think about 1.5mm-2mm left of the hub for a hub centric ring to grab. Every hub centric ring has a 45 degree bevel on the inside where it sits against the hub. So when the 5mm spacer is on there, the ring just wobbles and doesn't grab the hub. You can turn the ring around and it definitely grabs since that end is 90 degree cut on the inside. I thought about taking the ring and grinding the bevel on the outside and then turning it around to make it work.
Did a quick Google scan and I get this...
Not necessary: https://www.s2ki.com/forums/wheels-t...-rings-947753/

Not necessary: http://www.ft86club.com/forums/showthread.php?t=29670

80/20 split: http://www.ft86club.com/forums/showthread.php?t=74143

Looking up 5mm spacer on FRS/BRZ turns up nothing to show what people did using a 5mm spacer and aftermarket wheels to make it grab.

The stress will be on your wheel studs with out them. Certainly not necessary but a good idea to keep them. I doubt the wheel will fall off but check your studs at rotation.

From 949Racing: "Once the wheels are torqued, they [centering rings] are just along for the ride and neither support or transmit load."

In in 11 years of buying random aftermarket (some certainly not of renowned quality) I've never put hubcentric rings on them. I've never had an issue, seems more like a "just in case" or something that only seems apparent by science, not by example. I don't know how a spacer will affect this, but you're still using lug nuts to hold the wheel onto the hub, I don't see how it's different

On our car they are not necessary. Our wheels use conical lugs, where the lug nuts have a male taper and the wheel has a female taper around each bolt hole. These force the wheels to center around the studs when the lugs are tightened. The studs are centered around the hub. Centering rings are only necessary on wheels that have flat lug nuts, where the hub actually acts to center the ring during installation.



Once the wheel is installed, it is held in place by tension (clamping force) on the lugs, and to a small degree friction between the wheel and the hub. There is no shear force acting on the wheel/hub interface (there only would be the lug nuts were loose), and thus the ring itself has no structural role.


Anyone who says otherwise is simply wrong.

No.

Necessary? No.

They do relieve stress from your wheel when you torque your first lug nut though.

They are not that expensive its just good piece of mind

I remember someone doing the math and the result was the wheels are held on by friction. 5 lugs make an awful lot of clamping force.

Centering rings just make sure your wheels are centered

It's not the expense. I have three sets of them sitting around. It's just that they aren't working on the hub with a 5mm spacer.
I searched and the no bevel kind doesn't seem to exist so I'll just make the far right one and chop up one set I have to see how that works out.
It seems apparent we really don't need them but they're cheap and losing one set to experimentation won't hurt.

That's why I think I would like it on there, otherwise if you put the wheel up, it's just sitting on the lug threads.

Centering rings are a huge asset on european cars that have lug bolts instead of studs (VW, BWM, etc). It's a huge pain to get the first two bolts in on them if the wheel doesn't center on the hub. On cars with studs, not a problem at all to run without them.

If anybody else runs into this and wants the rings on there with the 5mm spacer, I found a set that has no bevel. Well not set, they're sold individually and kind of expensive for what they are.
4 for $42+ shipped to the US: https://www.nengun.com/rays/hub-rings They are "Rays Type NN hub ring". If they were more reasonably priced, I might have sprung for them but we can get
the regular ones and modify them for $10 shipped from Amazon all day long. I just ground off and sanded the edge like I pictured above to one of my sets and make them fit in reverse and it works.

Interesting find above. I ran into this small scenario when I bought my enkei RPF1s. 18x9.5 +38 couldn't clear my brembos so I needed a 10mm spacer. I go to put them on and realized the spacer is wider than my hub centric rings. so I was like well shit that sucks.. I tried to center it the best I could with my eyes/hands and went from there. So far so good.

Not meaning to derail/threadjack, but, any pictures of that fitment?