Thanks guys, will do some research with the links you provided and will see what I can come up with. In the meantime if anyone else has any links or ideas, by all means fill me in. Remember, the main two things I'm struggling with/am unsure of is finding a rubber compound that has good wear qualities and also the curing aspect of the whole thing since I'll be casting my tires in one piece in a mould where the rubber won't have too much air to cure with.