What is the Centerbore of a wheel?
The ‘centerbore’ of a wheel is the size of the hole at the back of the wheel which the ‘hub’ fits into. To help the wheels to seat properly this hole needs to be an exact match to the size of the hub.
Most modern wheels are what’s called ‘hub-centric’ – this means that the hub which protrudes from your car [and mates with the equivalent sized hole at the back of your wheel] is ‘load bearing’. All the studs or bolts do therefore is hold the wheel onto the hub!
Some people will say the term ‘lug-centric’. They are referring to the use of the lugs to position the wheel on the vehicle in the proper position. If you have’ lug-centric’ wheels, the state of your studs or bolts is obviously more critical – be sure to replace these from time to time and always 3/4 tighten the wheels off the car to ensure they’re centerd. However this is a term that should not really be used with modern day vehicles. Hub centric rings are the correct way to align a wheel properly on the vehicle.
Why are hub-centric rings so important?
As mentioned above these rings keep the wheel aligned on the vehicle hub while your fastening the wheel to vehicle. After the wheel is properly torqued the hub-centric ring does NOTHING! The ring is only used at the time of fastening.
Does the hub-centric ring material matter?
The answer here is NOT REALLY. Again these rings only are needed while fastening the wheel to the vehicle. While some people may think that metal is better because its stronger, there is no need for a strong ring because its not a structural piece. Additionally metal rings tend to corrode and can make it difficult to remove the wheel or the hub-centric ring from the vehicle.
The argument has also been made that plastic rings melt. Well while at some point this may be true, we have witnessed the use of race vehicles using them on track for multiple seasons without ever running into this melting problem.
–Portions Courtesy of YHI