Despite the best efforts of modern science, your car tires rarely last as long as you keep your car. At some time, they will wear out or become damaged and you will have to replace them. Many years ago, most people changed their own tires. Back then, old tires were a recycling nightmare. They were almost universally banned from city dumps and landfills. Having no other options available many people would simply chuck their old tires into a roadside ditch at night when no one was looking. Those few companies that were willing to take your old tires often would end up burning them. Burning tires, however, is an environmental disaster in almost every sense of the word. Arsenic, mercury, cadmium, lead, beryllium, chromium and other toxic and carcinogenic substances and dioxins are released into the air when a car tire is burned. Cardiac disease and respiratory problems can be caused by the metal particles released from a burning tire as well. Plus the natural resources that go into making a tire go to waste if the tire is burned.
Today all of that has changed. It had to change there really were no other options. It is estimated that 1.3 billion tires are sold every year and more than two thirds of those tires replace old worn out tires. That means that almost 1 billion tires worldwide are discarded annually. 20 years ago only 10 percent of all discarded tires were recycled but today more than 80 percent make it to a recycling facility. Recycling the material in old tires is a good idea no matter how you look at it and literally 100s of applications have been developed for recycling old car tires.
Almost no one changes their own tires anymore and the recycling of old tires is done by professionals who generally do so in an environmentally safe way. When you take your car in to have the tires changed at the local garage or tire shop there is almost always provision for taking your old tires for recycling. Approximately 1 in 4 of those old tires is retreaded and used again on another automobile somewhere. In many parts of the world old tires are ground up and used to make rubberized asphalt for highways or shredded and used as a base for gravel roads or as a sand or gravel substitute in some other road construction application. Some old tires are chopped up and used as part of the surface for indoor tennis courts or other indoor sports playing fields. For many applications, recycling old tire rubber is cheaper than collecting and processing new rubber.
The burning of tires has not completely disappeared but it has improved to the point where it is both environmentally safe and it recycles the raw materials. By using a process called pyrolysis, which burns the tires in a reduced air environment or vacuum, the raw materials are recovered and recycled. A typical car passenger tire will yield one kilogram of steel, four liters of oil, almost four kilograms of carbon and 850 liters of reusable combustible gas as a result of this recycling process.