[martindc1]

My guess is C Prepared, unless the classes have changed within the last few years. I used to compete pretty heavily with a Mustang in E Street Prepared. This involved using R compound racing tires. I would drive to the events on street tires with the racing tires in the back seat and trunk and then swap them to the R compounds once I got there. I generally used Hoosier but the Kumhos were good as well. In my experience of buying those tires, they were cheaper the smaller the rim diameter. So your best bet with those would be a 10 inch wheel in either 15 or 16. You could use a 15x10 factory steel wheel this way, provided you haven't put any crazy big brake system on your truck. In my experience, the big brakes weren't necessary for autocross either because of more weight and the fact that runs are only a minute or so. However, you could play with pad choice.