Technical Term
PCD (Pitch Circle Diameter)
The imaginary circle drawn through the center of the bolt holes.
Deep Dive
PCD is the most critical fitment metric. It is usually denoted as "Number of Bolts x Diameter" (e.g., 5x112 for Audi/VW, 5x120 for BMW). If the PCD does not match exactly, the wheel will not bolt onto the car. Wobble bolts can sometimes correct minor differences (e.g., 5x112 onto 5x114.3).
Related Concepts
Bolt PatternWobble BoltsCenter Bore