PCD stands for Pitch Circle Diameter. Also Known as Bolt Circle Diameter (BCD). The Bolt Circle Diameter (BCD) (or Pitch Circle Diameter – PCD) is the diameter of the circle that passes by the centre of the bolts.

For 4 Stud wheels you simply measure between the centre of two opposite bolts. Renault 4 stud wheels generally have a 4×100 PCD.	For 5 stud wheels you measure between the  centre of one bold and the end of the bolt opposite. Renault 5 stud wheels generally have a 5×108 PCD.