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Discussion Starter · #1 ·
Before we start modifying the car, we need to learn more about the data. It’s a passage about PCD and CB conversion. What’s PCD? What’s CB? Common data? Wheel spacers?

What does PCD means?
The Pitch Circle Diameter (PCD) is the diameter of the circle which passes through the centre of all the studs, wheel bolts or wheel rim holes.
The easiest way calculate the PCD is as follows:
1) Measure the distance ‘S’ between two adjacent studs from the centre of each hole.
2) Calculate from the formula below
Note: on 4 lug fitments you can measure from the center of one stud to the center of the stud directly opposite.
PCD Calculation Formula:
4 Stud PCD = S / 0.7071
5 Stud PCD = S / 0.5278
6 Stud PCD = S / 0.5


What does CB means?
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 millimeters. It’s also called hub centric.



In a case of installing wheel spacer, the kitted nuts are installed on the original car screws, the original nuts are installed on the wheel spacer studs. So when we change other sizes of wheel hub, install the wheel spacers to fit the wheel hub. Different sizes of wheel hub has different PCD.
CB is also the another data need to considerate when you want to change the wheel hub, the wheel spacer’s hub centric is contacted with wheel hub. So when we change other wheel hubs, the protruding part called hub centric need to fit the wheel hub.

Two cases of buying the wheel spacers:
Original size of wheel hub, provide the car model data to the official stuff.
Customized size of wheel hub, provide the car model and customized wheel hub PCD, CB data to the official stuff.


The common data in term of the most modification case.
As we know, many wheel hubs adopt the data 5x114.3PCD and 73.1CB, so I recommended it as a common data in the chart.
Thanks for reading.
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