For Dad's snowthrower that he uses on his concrete driveway I made skid shoes out of 2" wide by 1 1/2" thick and 6" long teflon blocks. His drive is 14' wide, 230' long. His garden tractor mounted snowthrower is only about 40" wide, so it takes quite a number of passes.
IIRC they were made for the winter of 2008 and they haven't worn out yet. They don't leave marks on the concrete like steel shoes would either. He leaves more marks from spinning the tires with chains on them..................
