A plastic or aluminum insert that fills the gap between a wheel's center bore and the vehicle's hub, ensuring the wheel centers on the hub rather than the lug bolts.
Hub centric rings (sometimes called hub rings or spigot rings) are small circular inserts made from plastic or aluminum that fit between the center bore of an aftermarket wheel and the vehicle's hub. Many aftermarket wheels have a larger center bore than the vehicle hub diameter to accommodate multiple vehicle fitments. That gap, if unfilled, means the wheel centers on the lug bolts rather than the hub face.
Centering a wheel on the lug bolts rather than the hub can cause vibration at highway speeds, uneven lug nut stress, and in extreme cases wheel runout problems. Hub centric rings eliminate the gap so the wheel seats correctly on the hub bore, which is the proper load-bearing surface. The result is smoother operation and more even distribution of forces across the hub face.
Hub centric rings are inexpensive (often sold in sets of four for under $20) and highly recommended any time an aftermarket wheel with a larger center bore is installed. Plastic rings are adequate for street use. Aluminum rings are preferred for track use or high-temperature applications because plastic rings can warp or melt from heat generated by heavy braking. Always verify the correct inside diameter (matching hub) and outside diameter (matching wheel center bore) before purchasing.