kilogram

iTrader: (1)

I know this is an old thread, but it's worth pointing out.

Technically, the only function of a hubcentric ring is to hold the wheel centered while it's being torqued. It does not take any load whatsoever once the wheel is torqued. If you run wheels that don't have center caps, you'll find the the ring can be moved with your fingers inside the wheel once it's torqued (unless it's corroded to the hub, see below), even with the car sitting on the ground. If they were meant to take any load at all, they would be a press fit.

They are not needed if you torque the wheels properly (2 passes, criss cross sequence, lift the wheel with your hand while tightening the first 2 lugs to help the nut center on the cone seat). Once the wheel is torqued, there is something like 50,000+lbs of clamping force holding the wheel to the hub (~10,100lbs per bolt @ 80ft-lbs for an M12 fastener). Static friction of aluminum on steel is ~0.61, meaning it would take over 30,000lbs of force parallel to the hub face to overcome the friction of the joint before even a single lb of load is transferred to the hub ring or studs. It is not the hub ring that takes the wheel's load, it is the friction between the hub and the wheel face.

Hub rings are merely installation tools. Once the wheel is installed, they do nothing. If the wheels were vibrating before the hub rings, they were installed improperly. Happens a lot at tire shops. They usually don't lift the wheel to help center it while the first couple lugs go on. The hub ring does this job for them, which is why the vibration usually goes away after they're installed.

I've also seen people around the internet say that your studs will break if you don't use them. This is false. The studs are loaded in tension only. There are 2 reasons they break:

1. They are too tight (beyond yield), and have encountered plastic deformation along their length.
2. They are too loose, so there is not enough friction to keep from loading the studs and tension is not high enough to negate the fatigue cycling.

Anodized rings won't corrode, but bare rings will. Galvanic corrosion occurs between two dissimilar metals in the presence of a conductive substance (water). Bare aluminum actually corrodes very quickly (which is why you need to etch the part with lye before anodizing), but aluminum oxide is mostly colorless. Anodizing is the process of artificially growing a layer of corrosion on the outer surface under controlled conditions. That corrosion is then dyed pretty colors.