What are spigot rings?

It's a ring that is fitted to the centre of your hub of a vehicle to decrease a bore size, normally used when aftermarket alloy wheels are fitted, or wheels are transferred from one make to another.

E.g. - Lexus wheels on a Honda, Toyota Wheels on a Nissan, and so on.

Spigots also aid the process of putting your wheel on centrally every time you take it off, so that you dont scrape the alloy with the thread from the hub.