Tire recycling

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]