tekneek -- The link below takes you to a chart within the asymmetrical ball layout section at buddiesproshop.com. The heading of the chart says "Track circumference versus tilt", but what you actually use is the circumferential diameter (the diameter of the track measured across the surface of the ball). There's another section at buddies that shows how to measure that. The relationship is between track diameter and tilt, the PAP has nothing to do with it. -- JohnP