I don’t understand your question… Use any type of tires you want, there are bonuses for using Toyo Tires, and you get 40% discount on Toyo R compound tires if you decide to use those.
As for class restrictions, it’s fairly detailed in the rulebook: If your car is street legal and has 12Lbs / Hp or greater, you’ll fit in A class. If you use R comps and have low power to weight ratio, you’ll be in B class. All other cars that are street legal with less than 12Lbs / hp, move up to C class. Race prepped cars or purpose built cars can run in D class.
Tires are wide open, but if you use premium tires like Hoosiers or any 2 grove R comps, that’ll push you up to D class automatically.
Hope this helps clarify.
All the information can be found at the ATTS web site: www.atts-online.ca
Hope to see some of you guys there.