This here a picture of the life cycle of a rubber tire. The beginning of the life cycle is extracting the materials from the Earth. The next step of the life cycle is manufacturing the tire. The tire is made from rubber, carbon black, and some chemicals. After the tire is manufactured it used by the vehicle for thousands of miles. After the tire is used the owner could return it to a recycling area to be made into mulch or it could be retreaded to be used again. The picture is from http://www.purcelltire.com/mining/sharing-knowledge/environmental-cycle.aspx
Here is some mulch that is made from used tires from vehicles. There are other ways you could use tires for anything. You could use the mulch for your plants or for a playground.