David,
Great questions. You can run those tires but they will need to be trued all the way down to where they have no tread. The easier and perfered method is to use the Thunderslot slick rear tires. Having said that, they are unavailable from any on-line slot car retailer in the States. I just ordered the last three bags (12 tires) from Armchair racer in Australia. I ordered three bags with the thought to sell some, at my cost, to other racers that can’t find them.
The slick tires will need to be glued and then trued to make sure they are 100% round. It makes a big difference in this series.
The blue #21 is being run by Russell. The difference is that Russell painted his from a white kit last year before the #21 was a stock item from Thunderslot. Crazy. It’s a beautiful version.