A 1995 report by the Scrap Tire Management Council states that there are approximately 900 million tires located in municipal solid waste landfills. During landfill fires, surface heat can melt tires buried below. More Tires than Cars Kimberley Harris, a market analyst for ISRI, says there is a wide range of markets for used tires in the United States, including the use of whole tires in reef construction, civil engineering projects, and erosion control, and the use of processed tires in brake pads and athletic and recreational surfaces. But Harris adds that, even with all of these potential markets, there are far more tires available than are needed.
Dirt is a big problem, as is chemical damage and damage from UV rays.
It's not just a matter of grinding up old tires and turning them into new ones. It would be nice if it were that simple, but it's not. The reason lies in the process that creates a tire from virgin rubber, says Romine. Rubbers, both natural and synthetic, are referred to as elastomers, and in their raw, unmodified form, are not only weak and adhesive, but lose elasticity with use, have physical properties that change markedly with temperature, and are degraded by air and sunlight. Obviously, that wouldn't make for a great tire, so what tire manufacturers settled on was a process called 'vulcanization,' where the virgin rubber is heated and combined with elemental sulfur.