If the track is pretty well packed/smooth I would start with a taper pin. If it's somewhat abrasive because of the sand/dirt reds would last longer, but if its clay like we have in the midwest, probably won't work. Silvers might be the ticket, but it really depends on the dirt for what compound. Here on clay-based tracks we use pink compound. If reds don't work at all, I would bet it is a pink track.
If the track isn't as smooth x-2000s or 3000s might be better, but if any sort of line sorts out a taper pin might be better again.
Front tires are really experimental, sometimes taper pins steer more, sometimes less.
Truck tires I would say for whatever compound run tapers front/rear as a starting point.