What is the PAX/RTP Index?
The PAX (Professional Auto-X) Index has been used by SCCA and other clubs for years. It is a handicapping system that attempts to account for performance differences between car classes, allowing the drivers’ performances to be compared. A PAX factor is assigned to each class; the faster the class, the higher the factor. The fastest cars have a PAX factor of 1.000; other PAX factors are a percentage based on performance potential relative to the fastest cars. Each driver’s actual time around the course is multiplied by their car’s PAX factor to calculate their PAX time. This PAX time is also called their indexed time or factored time. PAX times can then be compared across classes. The RTP (Racers Theoretical Performance) index is a separate set of indexes, calculated from different events, but basically similar. In 2002 both of these indexes were combined when a revised index was created called PAX/RTP. The PAX/RTP Index was developed and is maintained by Rick Ruth of Missouri and refl
