Just so you guys know they do still make gumbos. You either have to order them in a large amount from the company or there are a few places online that sell them ill see if I can dig it up.....
http://www.wheelingtire.com/catalog/Details.cfm?ProdID=41&category=8 http://www.ntwonline.com/acb/showdetl.cfm?&DID=48&Product_ID=1106&CATID=10 Honestly I have no idea how you guys that run higher than 15 or 20 make it anywhere unless there is some ground under that snow. When I had my 35 mtrs I tried those pressures and I couldnt even make it up the road to our spot. Those of you that run the mtrs and dont know about airing them down much. I ran mine on (15x10 steel rims not that good for holding beads aluminum rims have better lip to hold bead) at 4 psi and only blew 2 beads the whole year. Cruzila hit it right on the head with the pressures and the gumbos too. If I can get permission and a place to host it I have a pretty sweet snow wheelin video my friend made. Gotrocks has seen it he can attest to it. Any place to host that might need like a password where you cant download it just watch it from?