Open tire rule on the 3 types of tires. The tire that wins the race gets no "tire bonus" the best finishing car of the other 2 types receive a $100 bonus. Allow the 1070, f45 , f75. No fresh rubber. If they want to go through the trouble of buying them and then scuffing them somewhere else i guess that's what they will do.....check them as they come into the pits and mark them then.And keep track of what kind of tire each driver is using that day. More than 20 street stocks will show if you do this.