This relates to the center hole in the wheel that centers the wheel on the hub of the car. Since most wheels are mass produced, they have a large center bore to accommodate several different vehicles. If this is the case, it is recommended that you use a hub ring. Hub rings are hard plastic or metal ring that fits between the wheel and the vehicle. This centers the wheel perfectly on the hub ensuring that there is no run out when the wheel is installed on to the vehicle. Without hub rings it is possible to get vibrations even if the wheel / tire assembly is perfectly balanced.

The centerbore of a wheel is the machined opening on the back of the wheel that centers the wheel properly on the hub of a vehicle. This hole is machined to exactly match the hub so the wheels are precisely positioned as the lug hardware is torqued down. Keeping the wheel precisely centered on the hub when it is mounted will minimize the chance of a vibration. Some wheels are vehicle model specific and will come from the factory with a bore machined to match that vehicle. Some wheels are designed to fit multiple vehicle models and will use a centering ring system to reduce the bore size to match the hubs of different vehicles. These rings keep the wheel precisely positioned as the lug hardware is torqued down.

Some wheels are non-hubcentric by design. These are known as lug-centric wheels. With these wheels it is critical to torque the lug hardware with the vehicle on jack stands, off the ground. This allows the nuts or bolts to center the wheel and torque down without the weight of the vehicle pushing them off center.

The center bore of an alloy 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.

Some factory wheels have a centerbore that matches exactly with the hub to reduce vibration by keeping the wheel centered. Wheels with the correct centerbore to the car they will be mounted on are known as hubcentric. Hubcentric wheels take the stress off the lug nuts, reducing the job of the lug nuts to center the wheel to the car.

Wheels that are not hubcentric are known as lugcentric, as the job of centering is done by the lug nuts assuming they are properly torqued down. Centerbore on aftermarket wheels must be equal to or greater than that of the hub or the wheel cannot be mounted on the car. Many aftermarket wheels come with “hubcentric rings” that lock or slide into the back of the wheel to adapt a wheel with a larger centerbore to a smaller hub. These adapters are usually made of plastic but also in aluminium.

The centerbore of a wheel is the size of the machined hole on the back of the wheel that centers the wheel properly on the hub of the car. Centerbores on wheels are typically a standard size by brand or size (measured in inches or mm). Hub sizes vary by vehicle brand and style.

When this hole is machined to exactly match the hub so the wheels are precisely positioned, minimizing the chance of a vibration, it is said that the wheel is “hub centric”.

Some wheels require centering rings that lock into place in the back of the wheel in order to become hub centric and reduce the risk of vibration while driving. This is an acceptable alternative.

If you don’t not have hub centric wheels (lug centric), they should be torqued correctly while the vehicle is still off of the ground so they center properly. The weight of the vehicle can push the wheel off-center slightly while you're tightening them down if left on the ground.