What is PCD and why do I need to know it?

If you are looking to change your wheel rims, axle or wheel and tyre assembly, chances are you will need to know the Pitch Circle Diameter (PCD) of the wheel hub before you make your order. You don’t need a master’s degree in advanced mathematics, although sometimes it might feel like it, to work out your PCD…let us show you the easy way!


What is PCD?

The term PCD, or Pitch Circle Diameter, is often one that causes confusion and mayhem amongst workshop operatives, scrambling to calculate the size on scraps of paper and often leading to unnecessary delays and incorrect items being ordered.

PCD, in its simplest term 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.

Many products relating to wheel rims, axles or wheel and tyre assembly, require you to know the PCD when placing the order as this ensures the product is the correct fit for your vehicle or trailer.


How do I calculate PCD?

Step 1- Make a note of the tyre or rim size. This can help narrow down the PCD options further down the line and ensure you are ordering the correct item

Step 2- Identify how many lug nuts your wheel has. This is so you can identify which calculation you need to work out your PCD.

Step 3- Measure the distance from the centre of one lug not to the centre of the one next to it. This is the “S” figure (see the diagram below for more guidance)

Step 4- Using the below calculations you should be able to work out your PCD!

OR use our handy PCD calculator and save digging in the office drawers for the old school calculator that someone left lying around a few years back.

Pitch Circle Diameter – PCD Calculation Formula

4 Stud PCD =




5 Stud PCD =




6 Stud PCD =




Next Steps

Now you know what PCD is, and how to calculate it, browse our wheel rims, axle or wheel and tyre assembly products and trust that you’re picking out the right product from our 150,000 specialist parts and spares.

Still not sure? Not to worry- contact one of our friendly team members and they will be able to talk you through finding the right part for you- https://www.trailparts.co.uk/Contact_Us