A: Check with the race director to determine the rules around the class/classes you want to participate in.
- if its a spec type class then that will answer your question for you.
B: Ask the other racers what tire they are using.
We have an Outlaw SC class out here and any SC tire can be used. For hard packed clay/blue groove tracks, try the JC GooseBumps or the Proline BowTie M3.
For packed dirt or clay with dust/loose top layer (Our track) the Bowtie M2 is the best IMO, but the Goosebumps are favored by some and are working sweet on my DRT.