What is PCD, and how do I calculate it?

“I have no idea what my wheel P.C.D. is, nor do I know how to calculate it”, is an answer we frequently hear from customers.

The two main components for deciding on the installation of new wheels are

  1. PCD
  2. and wheel or rim offset.

The video below quickly identifies how to calculate wheel or rim offset.

wheel nut indicator

Click the image to purchase wheel indicators.

Technically, Pitch Circle Diameter (P.C.D.) is the diameter of the circle that passes through the centre of the wheel studs, wheel bolt holes, wheel rim holes or the bolt pattern. This information is particularly useful for selecting the correct alloy wheel rim.

Vehicle manufacturers have difficulty providing a wheel offset size because car buyers often change the tyre size.

P.C.D. or wheel stud pattern is needed when you wish to replace a worn axle, hub, drums or disc rotors.

It is impossible to provide the correct hub or electric drum without knowing the exact wheel stud pattern.

Couplemate recommends installing wheel nut indicators to help prevents loosening wheel nuts.

Wheel PCD Calculation Formula

  • 4 Stud PCD = Stud distance divided by 0.7071 to get PCD
  • 5 Stud PCD = Stud distance divided by 0.5878 to get PCD
  • 6 Stud PCD = Stud distance divided by 0.5 to get PCD

Example, 67.185mm / 0.5878 for a five stud with 1/2″ studs is 114.3mm, which is a Ford Stud Pattern.

Finally, download a list of PCD’s from Al-ko by clicking this link.

News article on wheel nut indicators.