Ahh. I get it now. I'm not familar with the rule book in detail.
Thanks for the help guys. The events I run are usually only classed as:
1. Novice -street tires
2. Novice - race tires
3. Experienced - street tires
4. Experienced - race tires
but they sometimes ask for your SCCA class to do pax timing. It's not a big deal but I don't want to to give the wrong info and get someone upset that might know.