Tire recycling, or rubber recycling, is the process of recycling waste tires that are no longer suitable for use on vehicles due to wear or irreparable damage. These tires are a challenging source of waste, due to the large volume produced, the durability of the tires, and the components in the tire that are ecologically problematic.[1]
Because tires are highly durable and non-biodegradable, they can consume valuable space in landfills.[1] If waste tires are improperly managed they may cause rubber pollution. In 1990, it was estimated that over 1 billion scrap tires were in stockpiles in the United States. As of 2015, only 67 million tires remain in stockpiles.[2] From 1994 to 2010, the European Union increased the amount of tires recycled from 25% of annual discards to nearly 95%, with roughly half of the end-of-life tires used for energy, mostly in cement manufacturing.[3][4]
Pyrolysis and devulcanization could facilitate recycling. Aside from use as fuel, the main end use for tires remains ground crumb rubber.[2][5] In 2017, 13% of U.S. tires removed from their primary use were sold in the used tire market. Of the tires that were scrapped, 43% were burnt as tire-derived fuel, with cement manufacturing the largest user, another 25% were used to make ground rubber, 8% were used in civil engineering projects, 17% were disposed of in landfills and 8% had other uses.[6] Globally, tire graveyards are a common environmental hazard, with significant pollutants and other challenges. For example, the Sulaibiya tire graveyard in Kuwait has had repeat highly toxic fires.[7]