Each year, more than a billion car tires reach the end of their service life, creating a formidable waste stream that challenges environmental management worldwide. The environmental footprint of tires begins well before disposal, stretching from tropical rubber plantations to urban roadways, and ultimately into soil, water, and air. The complexity of tire composition—over 400 chemicals and compounds, plus steel reinforcement—complicates both impact assessment and end-of-life solutions.
Natural rubber, predominantly sourced from smallholder farmers in Thailand, Indonesia, and Malaysia, accounts for about 70% of the rubber used in tires. Monocrop cultivation in these regions risks deforestation and biodiversity loss, while providing uncertain livelihoods. Alongside natural rubber, synthetic polymers, fillers, and chemical additives contribute to tire durability but also introduce environmental hazards. Tire wear releases microplastic particulates, now recognized as a major pollutant in oceans. Nick Molden, CEO of Emissions Analytics, notes, “We know enough to say that it is possibly the biggest, and possibly the least well understood, environmental problem related to transportation.”
One particularly alarming additive is 6PPD, an antioxidant that transforms into 6PPD-quinone during use. Edward Kolodziej of the University of Washington Tacoma describes 6PPD-quinone as “possibly one of the most toxic substances known to aquatic species,” linked to mass die-offs of coho salmon. This compound has been detected in diverse environments, from ocean sediments to human urine, yet its full ecological and health impacts remain unclear.
Disposal practices exacerbate the problem. Landfilling allows toxins to leach into soils and aquifers, while open burning emits harmful gases including carbon monoxide, nitrogen dioxide, and sulfur dioxide. The circular economy model—aiming to reduce, reuse, and recycle materials in closed loops—offers potential pathways for tire waste management, but current recovery rates are low. A 2019 Tire Industry Project report found that in 45 surveyed countries, only 42% of end-of-life tires were used in material recovery and 15% in energy recovery.
Common recovery methods include shredding tires into rubber pellets for construction filler, asphalt modification, or artificial sports pitches. Tire-derived fuel, burned in cement, steel, and paper production, is promoted for its low cost and potential CO2 reductions. Gavin Whitmore of TIP states, “Successful ELT management systems … foster circular flows of materials … and avoid the unregulated dumping of tires.” However, grinding and burning often amount to downcycling, and practices like rubber crumb use on sports fields contribute to microplastic pollution, prompting regulatory bans in the European Union.
Two technologies—devulcanization and pyrolysis—show promise for higher-value recovery. Devulcanization breaks sulfur bonds in rubber, producing material that can partially replace virgin rubber in new tires. Jon Visaisouk of Tyromer says his company processes 100,000 to 150,000 waste tires annually into devulcanized rubber. Yet, as patent attorney Niles Beadman points out, “You can’t use that devulcanized product as 100% raw material.”
Pyrolysis heats tires without oxygen, yielding recovered carbon black, oils, and gases. Vianney Vales, CEO of Wastefront, claims, “What we’re bringing to the table is a solution that is not only environmentally friendly, but can work at scale to actually make a dent in the problem.” Steel is removed prior to processing, and gases can power the system itself. While advocates call pyrolysis “environmentally safe,” researchers such as Dina Czajczyńska warn of toxic sulfur emissions and variable product quality. Pakistan’s ban on pyrolysis units underscores pollution concerns. Thomas Sörensson of Scandinavian Enviro Systems emphasizes using “the latest technology for reducing emissions, taking care of sulfur, and … meeting the highest environmental regulations.”
Addressing tire waste also requires upstream changes. The Zoological Society of London highlights opaque rubber supply chains that may conceal deforestation impacts. Alternative sources like Russian dandelion offer potential, with Dirk Prüfer of the University of Münster noting its ability to grow on marginal lands without competing with food crops. Yet Sam Ginger of ZSL cautions against diverting attention from sustainability issues affecting millions of smallholder farmers.
Experts advocate regenerative agricultural practices, agroforestry, and empowering farmers as entrepreneurs to integrate circular principles into production. Stefano Savi of the Global Platform for Sustainable Natural Rubber stresses that by reducing pesticides and improving water management, “you will be able to do more with less.” Achieving transparency in supply chains will require collaboration across industries, including financial contributions from car manufacturers.
Some researchers argue that material-focused recycling alone will not suffice. Czajczyńska underscores reducing overall car use: “No matter how well you process or treat waste tires, [they] will always produce some emissions or another waste product.” Kaustubh Thapa of Utrecht University adds that a technocratic approach risks shifting problems elsewhere, and that the social dimension must be included in circular economy strategies.