PCD stands for Pitch Circle Diameter — the diameter of the circle that passes through the center of every wheel stud, bolt, or rim hole on a wheel. It's one of the basic measurements, alongside offset and center bore, that determines whether a wheel will physically bolt onto a given hub.
How to Measure It
Measuring PCD starts with a single distance, "S" — the straight-line distance between two adjacent stud or bolt hole centers. From there, the pitch circle diameter is calculated using a formula that depends on the number of studs.
PCD Formulas by Stud Count
- 4-stud PCD = S ÷ 0.7071
- 5-stud PCD = S ÷ 0.5878
- 6-stud PCD = S ÷ 0.5
Why PCD Matters
PCD is a fixed measurement set by the vehicle manufacturer, and any wheel installed on that hub has to match it exactly — there's no adjustment or tolerance range the way there is with offset. It's a basic reference point worth knowing alongside bolt pattern, center bore, and offset whenever wheel or fitment questions come up in the context of a brake upgrade.