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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:

  1. Identify the size of the rim or tyre size. (This helps to narrow down the likely PCD sizes)
  2. Measure the distance ‘S’ between two adjacent studs from the centre of each hole.
  3. Using the calculator enter the number of studs/holes & ‘S’ and press ‘calculate’.
  4. 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

Pitch Circle Diameter - 4 stud/holes

PCD with 5 Studs/Holes

Pitch Circle Diameter - 5 stud/holes

PCD with 6 Studs/Holes

Pitch Circle Diameter - 6 stud/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 91.92mm 130mm
13″ 4 98.78mm 139.7mm (5½”)
13″ 5 82.29mm 140mm
13″ 5 97.04mm 165.1mm (6½”)
14″ 4 70.71mm 100mm
14″ 5 65.83mm 112mm
14″ 5 82.29mm 140mm
14″ 5 89.58mm 152.4mm (6″)
14″ 6 102.5mm 205mm
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 caravans and trailers the popular pitch circle diameters are:

Imperial = 4″, 5½” and 6½”

Metric = 100mm, 112mm, 115mm,130mm, 140mm and 205mm

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