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Discussion Starter #1 (Edited)
I've looked around on the forums a bit to see what others' experiences have been with using differently sized center bore wheels, however I'm not having much luck answering my question. Last winter, I ran on 72mm steel wheels with no hub centric rings (it's impossible to find 72mm OD x 70.3mm ID). I didn't have any vibration problems, however I'm worried about the stresses applied to the lugs.

Given that the steel wheels are not hub centric, I'm worried about another season of shear stresses on the lug nuts. I have some hub centric rings that are 72.6mm OD x 70.3mm ID that I've tried sanding down, but the tolerances are so poor that it looks like it's a futile effort. Besides, how can a plastic ring be load bearing???

Edit: From what I've read, and what seems appropriately logical to me, is that it's the normal force created by the lug nuts tightening the wheel against the hub that provides enough static friction to handle the shear loads. Any mechanical engineers or mechanics out there who know the right answer?

Thanks for your advice.
 

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I always wonder about this too. I'm a mechanical engineer but not at all a wheel/tire expert. I know they say that OEM designs are hubcentric, but I have trouble seeing how the clearance between a hub and wheel bore can be so tight that it is not overcome by the size and position of the nesting cones on the lug nuts and wheel. Especially in 5-10 years when everything is rusted out and the sizes have changed.

When I install wheels on my cars, I run all lug nuts down hand-tight. Then I go back and do them again while shaking the wheel a little, and at least some will always turn down a little more by hand. I take this to mean the wheel is centering itself on those nesting cones - which means alignment is lug-centric.

I agree that the hubcentric rings can't possibly support a load. The only thing they can possibly do is help with alignment of the center of the wheel to the center of the hub (and then in that case, with a plastic bearing surface that moves under load, how it not a lug-centric system?). If you want to put rings in there but have an odd size, two ideas are either to 3D print them or wrap shim stock around the hub.
 

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These two should be enlightening:

Interesting illustration of potential issues in this one:
 

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I bought the Cruze diesel steel wheels last year when I bought my winter wheels. Same bolt pattern and hub size as the Volt. 16x6.5 et 40 if I'm not mistaken.
The center bore is there to center the wheel to the hub. If the wheel is slightly misaligned it could feel like a tire is unbalanced. This will be amplified the faster you go. Cars equipped with studs are less likely to feel this compared to lug bolts, but can still happen. I always try to buy wheels which are hubcentric. If not I always use rings.
 

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Hi Steverino, thanks for posting. I've read many articles on the subject, those videos were more helpful than all of them. They agreed with us that the lugs nuts are supporting the vehicle weight, not the hub (if it were the other way around, the hub/bore bearing surfaces would have to be so close together that you wouldn't be able to get the wheel on). It makes much more sense that a wheel falls off from nuts vibrating loose than it does from the studs shearing off. A good reminder to check torque every once in a while.

So OP, if they don't make rings in your size and you wanted to use material to center the wheel on the hub I'd probably wrap plastic shim stock with a thickness of less than .85 mm (.034") around the hub. Maybe go .005"-.010" less so you can get them on. Something like this would even allow you to tune it for about the same cost as the rings:

https://www.amazon.com/TTC-Color-Co...1512740686&sr=8-1&keywords=plastic+shim+stock

If you have a friend or a local library with a 3D printer, that could work too.
 
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