The centre bore is the size of the hole in the centre of the wheel where the spigot fits through. The centre bore, (also known as spigot size), is the diameter of this hole, usually measured in millimetres.
For most road wheels, the weight of the car is transmitted from the spigot, (the bit the centre of the wheel that protrudes from the hub), to the centre hole in the wheel. The job of the wheel studs or wheel bolts is to hold the wheel in place over the spigot. It is therefore very important that the centre bore of the wheel matches the spigot size of the car's hub.
It is possible to use spigot rings to adapt the size of the centre bore, and spigot rings are available in all the useful sizes from places like eBay. Of course this only works if the wheels have a larger centre bore than the car's spigot ring. If the wheel's centre bore is too small, then the only way they could be made to fit would be if they were machined, (ie bored out), which is so costly it makes it pretty much impractical.
GUIDE to Offset, Lug Pattern, Wheel/Tires Specs
Video explaining EVERYTHING about wheels and fitment. I go over what offset means, what lug patterns are, and how to read wheel and tires measurements and specs. This is only Part 1, Part 2 will go over Spacers, Hubcentric rings, Lug Bolts, Coilovers, etc.
GUIDE to Spacers, Lug Bolts
This is part 2 of stance and wheel fitment guide. In this part I explain Spacers and extended lug bolts.
Custom wheel center bore
Uploaded by Darko HPG on 2013-03-21.
What is the centre bore?
The offset of a vehicle's wheel is the distance between the centerline of the wheel and the plane of the hub-mounting surface of the wheel. It can thus be either positive or negative, and is typically measured in millimeters. Offset has a significant effect on many elements of a vehicle's...
Bolt Pattern/Pitch Circle Diameter (PCD)
PCD (Pitch Circle Diameter) is the measurement of the diameter of the imaginary circle drawn through all of the wheel bolts or studs on a wheel. It is also known as the 'bolt circle'. A wheel's PCD is usually displayed after the number of studs, separated by a slash. Hence a 'pcd' of 5/120 means...