The PCD (pitch circle diameter) is the diameter of the circle, where the holes/studs for the wheel mounting are located. The PCD is indicated in millimeters. The first figure quantifies the number of holes/studs for the wheel mounting, the second figure quantifies the diameter.

Example: 5x205 PCD means: This pitch circle diameter has five holes/studs for the wheel mounting and they are located on a circle with a diameter of 205 millimeter.