How to calculate the PCD – Pitch Circle Diameter.
from Western Towing – www.westerntowing.co.uk
The Pitch Circle Diameter (PCD) is the diameter of the circle that passes through the centre of all the studs, wheel bolts or wheel rim holes. The easiest way to calculate the PCD is as follows:
- Identify the size of the rim or tyre size. (This helps to narrow down the likely PCD sizes)
- Measure the distance ‘S’ between two adjacent studs from the centre of each hole.
- Using the calculator enter the number of studs/holes & ‘S’ and press ‘calculate’.
- Using the relevant diagram depending on the number of studs you have you should be able to identify the correct PCD.
Note:
Imperial sizes are commonly used on UK trailers whereas European trailers use metric.
PCD with 4 Studs/Holes
PCD with 5 Studs/Holes
PCD with 6 Studs/Holes
Pitch Circle Diameter – PCD Calculator
Popular wheel Sizes & Stud Patterns
| Rim Size | Studs |
S | PCD |
|---|---|---|---|
| 8″ | 3 | 76.90mm | 88.8mm |
| 8″ | 3 | 95.26mm | 110mm |
| 8″ | 4 | 70.71mm | 100mm |
| 8″ | 4 | 71.84mm | 101.6mm (4″) |
| 8″ | 4 | 81.32mm | 115mm |
| 8″ | 4 | 91.92mm | 130mm |
| 10″ | 4 | 70.71mm | 100mm |
| 10″ | 4 | 71.84mm | 101.6mm (4″) |
| 10″ | 4 | 79.20mm | 112mm |
| 10″ | 5 | 65.83mm | 112mm |
| 10″ | 4 | 81.32mm | 115mm |
| 10″ | 4 | 91.92mm | 130mm |
| 10″ | 4 | 98.78mm | 139.7mm (5½”) |
| 12″ | 4 | 70.71mm | 100mm |
| 12″ | 4 | 71.84mm | 101.6mm (4″) |
| 12″ | 5 | 65.83mm | 112mm |
| 12″ | 4 | 91.92mm | 130mm |
| 12″ | 4 | 98.78mm | 139.7mm (5½”) |
| 12″ | 5 | 82.29mm | 140mm |
| 12″ | 5 | 97.04mm | 165.1mm (6½”) |
| 13″ | 4 | 70.71mm | 100mm |
| 13″ | 4 | 79.20mm | 112mm |
| 13″ | 5 | 65.83mm | 112mm |
| 13″ | 4 | 80.82mm | 114.3mm (4½”) American |
| 13″ | 5 | 67.2mm | 114.3mm (4½”) American |
| 13″ | 4 | 91.92mm | 130mm |
| 13″ | 4 | 98.78mm | 139.7mm (5½”) |
| 13″ | 5 | 82.29mm | 140mm |
| 13″ | 5 | 97.04mm | 165.1mm (6½”) |
| 13″ | 4 | 70.71mm | 100mm |
| 14″ | 5 | 65.83mm | 112mm |
| 14″ | 4 | 80.82mm | 114.3mm (4½”) American |
| 14″ | 5 | 67.2mm | 114.3mm (4½”) American |
| 14″ | 5 | 82.29mm | 140mm |
| 14″ | 5 | 89.58mm | 152.4mm (6″) |
| 14″ | 6 | 102.5mm | 205mm |
| 15″ | 4 | 80.82mm | 114.3mm (4½”) American |
| 15″ | 5 | 67.2mm | 114.3mm (4½”) American |
| 16″ | 5 | 97.04mm | 165.1mm (6½”) |
Pitch Circle Diameter – PCD Calculation Formula
| 4 Stud PCD = | S |
| 0.7071 | |
| 5 Stud PCD = | S |
| 0.5878 | |
| 6 Stud PCD = | S |
| 0.5 |
How to find the Offset of a wheel rim
Please Click Here If you need to find the OFFSET of the wheel rim.
Frequently Asked Questions
What does PCD mean?
PCD is short for Pitch Circle Diameter, which is the diameter of the circle that passes through the centre of the bolt holes or studs on a hub or drum. This is the same as the mounting holes on a wheel rim.
How do I calculate the PCD?
The PCD or Pitch Circle Diameter can be calculated by using some simple formulas depending on how many studs, wheel bolts or bolt holes there are.
If ‘S’ is the distance between two adjacent studs/bolts or holes (measured in millimetres) then the PCD would be:
4 studs/bolts or Holes = S ÷ 0.7071
5 studs/bolts or Holes = S ÷ 0.5878
6 studs/bolts or Holes = S ÷ 0.5
What are popular Pitch Circle Diameters?
PCD measurements vary depending on the application, for European caravans and trailers the popular pitch circle diameters are:
Imperial = 4″, 5½” and 6½”
Metric = 100mm, 112mm, 115mm,130mm, 140mm and 205mm
There are some American trailers & caravans in Europe with pitch circle diameters:
Imperial = 4½” and 6″
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