Machining wheel centres

Centre spigot size
This is a tricky one. The wheel bolts or
studs are there to hold the wheel laterally on to the axle, but they're
not really designed to take vertical load - ie. they're not designed to
take the weight of the car. That's the job of the centre spigot - the
part of the axle that sticks out and pokes through the hole in the
middle of the wheel. It's the load-bearing part of the axle and the
wheel, as well as being the assembly that centres the wheel on the
axle. For the most part, the centre spigot on aftermarket alloy wheels
is much larger than that of the car you want to put them on to. When
this happens, the best solution is a spigot locating ring (also called
a hub-centric ring) which is essentially a steel or hard plastic
doughnut designed to fit snugly on to your axle spigot and into the
wheel spigot.

H wrote:The centre hole is very important - it needs to be the right size, not just bigger than the central stub - the wheel nuts/bolts hold the wheel on, the central "nubbin" bit stabilizes the whole wheel and is load bearing - for best handling it needs to fit and be "round", not slop around