I have found that the best runners that you can put on your sleds is what we call up here "puck board". It is the composite strip about 6" wide 1/4" thick along the bottom of the hockey boards in your local arena. They are replaced on a regular basis and up here, the price is right. They are easily cut to size on a table saw. Counter sink the holes and you have a set of runners that will last the lifetime of your sled!! Go to your nearest arena and tell them that you will do them a huge favour by hauling the old ones away. Usually they will be more than happy to get rid of them.