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. Identify the size of 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.
Please Click Here If you need to find the OFFSET of the wheel rim.