How to Use Calipers to Measure Alloy Wheel Centre Caps Accurately

When approaching an alloy wheel hub, you must measure distinct layout parameters to guarantee a perfect mechanical fit:

Outermost Face Diameter: The maximum exterior width of the visible cap or recess pocket.
Inner Clip Diameter: The measurement across the expansion tabs that physically grip the wheel bore.
Adhesive Recess Depth: The structural step down from the wheel face to the mounting plane.
Total Hub Clearance: The gap between the backside of the cap and the protruding axle lock nut.