Center Bore Check
The wheel's center bore must be at least your hub's diameter. Equal is hub-centric (ideal). Larger needs a hub-centric ring to center the wheel. Smaller will not go on. Pick your vehicle or type the hub size to run the center bore check.
Hub diameters shown for our vehicles are candidate values
pending verification — measure your hub (outer diameter of the raised center
boss) with calipers before ordering rings. A lug-centric wheel run without a ring
can be a few tenths off-center and cause a speed-dependent vibration.
Why can't I find my car's center bore in the owner's manual? →
Hub-centric vs lug-centric
- Hub-centric: the wheel bore sits snugly on the hub, which centers the wheel and carries its weight. The lug nuts only clamp. This is how OEM wheels fit.
- Lug-centric: the bore is oversized (aftermarket wheels are often made with one large bore to fit many cars) and the wheel is centered only by the cone seats of the lug nuts. Usually fine if torqued evenly in sequence, but a hub-centric ring — a plastic or aluminum sleeve sized wheel-bore → hub — removes the guesswork.
- Bore smaller than hub: the wheel physically will not seat. Do not have the bore machined out unless the wheel maker approves it.
How to measure center bore and hub diameter
- Wheel center bore: with the wheel off the car, put the inside jaws of a caliper into the bore from the back (hub) side and read the widest point across the center. Measure the straight part the hub slides into, not a chamfer or the cap recess on the face. Take two or three readings, turning the caliper, and use the largest.
- Vehicle hub: with the wheel off, put the outside jaws across the raised center boss (the hub pilot), not the wider flange behind it.
- Ring size: a hub-centric ring's outer diameter is the wheel bore and its inner diameter is the hub. Enter both numbers above and the tool names the ring.
A tape measure or ruler is not precise enough: use a caliper or a dedicated center bore gauge. The wheel maker's spec sheet usually lists the bore, which saves measuring the wheel.
Reading ring sizes
Rings are sold as outer diameter → inner diameter, e.g. 73.1 → 66.6 fits a 73.1 mm wheel bore onto a 66.6 mm hub. The tool prints exactly that.