PCD (Pitch Circle Diameter)
The diameter of the imaginary circle that passes through the centre of every lug hole on a wheel hub.
PCD — Pitch Circle Diameter — is one of the two numbers in a bolt pattern. For a 6×139.7 wheel, 139.7 mm is the PCD: imagine a circle drawn through the centre of all six lug holes; that circle's diameter is the PCD.
PCD must match exactly between wheel and hub. A 0.7 mm PCD mismatch (e.g. 139.7 vs 140) cannot be safely shimmed — the wheel will not centre on the studs and the lugs will shear under braking and cornering loads.
See also