I believe your tire question was answered on the other forum. A shifter class Road Racer (or WKA official) will have to help you with the specific regs for each of these class options.
This raises yet another issue, with no “online” rules and regs it’s very tough for a TEMP member to be sure which class to choose if pre-entering. Especially when time is short to take advantage of pre registering.
I know why it isn’t downloadable (insurance requirements/lack of compensation) and they are solid reasons no doubt. But, we as participants, should question and be concerned that TEMP members may not be completely educated or compliant with these rules/regs. There needs to be a way for TEMP members to secure the proper info before attending an event, after all, they do pay a fee for the right to compete.
If you get no input here contact Keith @ WKA : email@example.com
and ask for some guidance on class choice.