You wont find anything that is going to keep the mud from sticking to the tires when your using the tires to roll in a wet muddy track, its just not going to happen. Only real solution is to get yourself an old set of tires and only use that set for rolling in the track, or use vehicles to pack the track. I refuse to take my kart out and pack the track in like other people will do, ill sit back and let everyone else do it, i spend far too much time cleaning and getting my stuff ready to race each week to go out for 5 minutes and the entire kart be caked in 50lbs of mud. I just wont do it