Why is tire rubber not biodegradable?

Answer 1

Actually, tire rubber IS biodegradable. The reason why roads aren't covered with a layer of rubber from tire treads is because tiny bacteria eat the rubber particles.

However, individual tires can last many years -- or decades -- outdoors before finally breaking down from exposure to the elements. Tires also trap water, creating breeding ponds for mosquitoes or other insects. And fires in a big pile of tires are almost impossible to put out.

All this means that old tires can indeed create environmental problems. But they are biodegradable ... eventually.