The PAX index was developed by Rick Ruth and reflects study of results from well over 500 nationwide Solo events. The below information is sourced from the official PAX webpage.
| Category | Class | Multiplier (2015) | Multiplier (2014) | Difference |
|---|---|---|---|---|
| Street | A Street | 0.829 | 0.833 | -0.004 |
| Street | B Street | 0.826 | 0.831 | -0.005 |
| Street | C Street | 0.814 | 0.821 | -0.007 |
| Street | D Street | 0.812 | 0.815 | -0.003 |
| Street | E Street | 0.808 | 0.814 | -0.006 |
| Street | F Street | 0.810 | 0.818 | -0.008 |
| Street | G Street | 0.806 | 0.806 | 0 |
| Street | H Street | 0.796 | 0.797 | -0.001 |
| Street | Super Street | 0.835 | 0.843 | -0.008 |
| Street R | Super Street R | 0.859 | 0.860 | -0.001 |
| Street Touring | Street Touring R | 0.838 | 0.838 | 0 |
| Street Touring | Street Touring Sport | 0.828 | 0.829 | -0.001 |
| Street Touring | Street Touring Ultra | 0.844 | 0.846 | -0.002 |
| Street Touring | Street Touring Xtreme | 0.831 | 0.827 | 0.004 |
| Street Touring | Street Touring FWD | 0.801 | 0.801 | 0 |
| Street Prepared | A Street Prepared | 0.865 | 0.866 | -0.001 |
| Street Prepared | B Street Prepared | 0.863 | 0.863 | 0 |
| Street Prepared | C Street Prepared | 0.861 | 0.861 | 0 |
| Street Prepared | D Street Prepared | 0.854 | 0.855 | -0.001 |
| Street Prepared | E Street Prepared | 0.849 | 0.849 | 0 |
| Street Prepared | F Street Prepared | 0.840 | 0.839 | 0.001 |
| Street Prepared | Super Street Prepared | 0.871 | 0.872 | -0.001 |
| Street Modified | Street Modified | 0.870 | 0.870 | 0 |
| Street Modified | Street Modified FWD | 0.853 | 0.851 | 0.002 |
| Street Modified | Super Street Modified | 0.882 | 0.882 | 0 |
| Prepared | B Prepared | 0.881 | 0.881 | 0 |
| Prepared | C Prepared | 0.864 | 0.864 | 0 |
| Prepared | D Prepared | 0.879 | 0.879 | 0 |
| Prepared | E Prepared | 0.874 | 0.876 | -0.002 |
| Prepared | F Prepared | 0.880 | 0.883 | -0.003 |
| Prepared | X Prepared | 0.905 | 0.906 | -0.001 |
| Modified | A Modified | 1.000 | 1.000 | 0 |
| Modified | B Modified | 0.964 | 0.965 | -0.001 |
| Modified | C Modified | 0.919 | 0.922 | -0.003 |
| Modified | D Modified | 0.918 | 0.920 | -0.002 |
| Modified | E Modified | 0.922 | 0.926 | -0.004 |
| Modified | F Modified | 0.926 | 0.924 | 0.002 |
| Modified | Kart Modified | 0.955 | 0.957 | -0.002 |
| Formula | Formula SAE | 0.984 | 0.989 | -0.005 |
| Formula | Formula Junior A | 0.878 | 0.880 | -0.002 |
| Formula | Formula Junior B | 0.842 | 0.842 | 0 |
| Formula | Formula Junior C | 0.734 | 0.741 | -0.007 |
| CAM | Classic American Muscle Contempory | 0.830 | 0 | |
| CAM | Classic American Muscle Sport | 0.836 | 0 | |
| CAM | Classic American Muscle Traditional | 0.825 | 0 | |
| Category | Class | Multiplier (2015) | Multiplier (2014) | Difference |
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