Is it possible to buy your carpet foam inserts for different tire types separate? For example, the stadium truck carpet foams?

As part of that, how do the stadium truck carpet foams compare to your foams you include with your dirt style tires like the stadium truck goosebump? Looking at foams here since the track is bumpy for your molded inserts that are pretty stiff for these conditions, but don't see the foams to be bought anywhere and comparing how the carpet and "dirt" style foams feel by hand.