What does CB mean?
CB refers to the Centre Bore.
The Centre bore is the diameter of the hub spigot and/or the locating hole in the back of the wheel. Volkswagen have many models with a 57.1 CB meaning the diameter of the locating spigot on the hub is 57.1mm. To calculate this, measure the diameter of the spigot from edge to edge. For custom jobs, we may also ask for the hub spigot length.