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 (2026) | Multiplier (2025) | Difference |
|---|---|---|---|---|
| Street | A Street | 0.830 | 0.826 | 0.004 |
| Street | B Street | 0.823 | 0.819 | 0.004 |
| Street | C Street | 0.814 | 0.813 | 0.001 |
| Street | D Street | 0.811 | 0.811 | 0 |
| Street | E Street | 0.788 | 0.790 | -0.002 |
| Street | F Street | 0.817 | 0.817 | 0 |
| Street | G Street | 0.793 | 0.794 | -0.001 |
| Street | H Street | 0.780 | 0.784 | -0.004 |
| Street | Super Street | 0.837 | 0.836 | 0.001 |
| Solo Spec | Solo Spec Coupe | 0.808 | 0.809 | -0.001 |
| Street Touring | A Street Touring | 0.836 | 0.834 | 0.002 |
| Street Touring | B Street Touring | 0.835 | 0.833 | 0.002 |
| Street Touring | C Street Touring | 0.829 | 0.830 | -0.001 |
| Street Touring | D Street Touring | 0.820 | 0.818 | 0.002 |
| Street Touring | E Street Touring | 0.815 | 0.815 | 0 |
| Street Touring | G Street Touring | 0.812 | 0.810 | 0.002 |
| Street Touring | Super Street Touring | 0.838 | 0.837 | 0.001 |
| Street Prepared | A Street Prepared | 0.852 | 0.851 | 0.001 |
| Street Prepared | B Street Prepared | 0.856 | 0.855 | 0.001 |
| Street Prepared | C Street Prepared | 0.858 | 0.859 | -0.001 |
| Street Prepared | D Street Prepared | 0.854 | 0.847 | 0.007 |
| Street Prepared | E Street Prepared | 0.842 | 0.840 | 0.002 |
| Street Prepared | F Street Prepared | 0.833 | 0.831 | 0.002 |
| Street Prepared | Super Street Prepared | 0.860 | 0.857 | 0.003 |
| Street Modified | Street Modified | 0.870 | 0.868 | 0.002 |
| Street Modified | Street Modified FWD | 0.857 | 0.850 | 0.007 |
| Street Modified | Super Street Modified | 0.878 | 0.878 | 0 |
| Prepared | B Prepared | 0.875 | 0.874 | 0.001 |
| Prepared | C Prepared | 0.862 | 0.863 | -0.001 |
| Prepared | D Prepared | 0.863 | 0.865 | -0.002 |
| Prepared | E Prepared | 0.855 | 0.858 | -0.003 |
| Prepared | F Prepared | 0.877 | 0.877 | 0 |
| Prepared | X Prepared | 0.892 | 0.890 | 0.002 |
| Modified | A Modified | 1.000 | 1.000 | 0 |
| Modified | B Modified | 0.966 | 0.978 | -0.012 |
| Modified | C Modified | 0.896 | 0.899 | -0.003 |
| Modified | D Modified | 0.906 | 0.906 | 0 |
| Modified | E Modified | 0.916 | 0.916 | 0 |
| Modified | F Modified | 0.917 | 0.917 | 0 |
| Modified | Kart Modified | 0.936 | 0.937 | -0.001 |
| Formula | Formula SAE | 0.965 | 0.980 | -0.015 |
| CAM | Classic American Muscle Classic | 0.827 | 0.825 | 0.002 |
| CAM | Classic American Muscle Sport | 0.847 | 0.844 | 0.003 |
| CAM | Classic American Muscle Traditional | 0.819 | 0.821 | -0.002 |
| Xtreme Street | Xtreme Street A | 0.861 | 0.846 | 0.015 |
| Xtreme Street | Xtreme Street B | 0.859 | 0.848 | 0.011 |
| Xtreme Street | Xtreme Street Unlimited | 0.869 | 0.869 | 0 |
| Electric | Electric Vehicle | 0.839 | 0.839 | 0 |
| Club Spec | Club Spec Mustang | 0.794 | 0.800 | -0.006 |
| Club Spec | Club Spec MX-5 | 0.803 | 0.812 | -0.009 |
| Heritage Classic | Heritage Classic Race Tire | 0.813 | 0.814 | -0.001 |
| Heritage Classic | Heritage Classic Street Tire | 0.789 | 0.789 | 0 |
| Category | Class | Multiplier (2026) | Multiplier (2025) | Difference |
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