The next time you have a big rodeo or anything involving horses, take a bunch over there. I've gotten rid of a lot of tires this way-them guys lay the tires down for mats in the trailers so the horses have some padding to stand on. I usually will cut them up myself before I go. With the help of a friend to assist in holding the tire, just take a utility knife and cut the sidewall / bead from the tread-they cut very fast and easy if you go right down the bottom of a groove. Then all that you have to throw away is the sidewall / bead rings, which will hide in your favorite neighborhood dumpster quite easily. Also, if you notice any start up machine shops, sometimes they will take them to use as floor mats in front of mills, lathes, etc...