Tires contain a variety of chemicals and metals that should not be consumed by humans. They do gradually erode and degrade, releasing chemicals into the environment. It is because of these pollution concerns that it is so difficult to legally dispose of old tires. That brings us to the other side of the argument: because it's so difficult to legally dispose of old tires, they're piling up and causing a real waste problem. You'd think that any opportunity to put old things to good use, such as growing food, would be worthwhile.
correct me if i'm wrong
(hope it helps)
