Why Do We Recycle Tires?

tire fire

Tire fires of past decades could take months to extinguish, while emitting smoke thick containing cyanide, carbon monoxide, and other toxins.

Until 19 years ago, countless illegally dumped tires polluted our state. Large piles of old tires sometimes even caught fire in the hot California sun. These tire fires put off toxic smoke containing cyanide and carbon monoxide. Because a fire can continue to burn deep inside a pile of tires after the top layer appears extinguished, firefighters struggled to put out these smoldering blazes that emitted thick, black plumes of toxic smoke that sometimes burned for months.

California turned to recycling to solve the problem of tires:

  1. Catching fire
  2. Clogging waterways
  3. Filling with water that bred disease-causing mosquitoes

tire pile

Where can we put 51 million tires a year?

California’s 35 million registered vehicles generate 51 million used tires every year. To manage this constant flow of vulcanized rubber into the waste stream, California passed the Tire Recycling Act in 1989, which created the Tire Recycling Program. After a series of devastating illegal tire pile fires in 1998 and 1999, the law was strengthened in 2000.

To prevent illegal stockpiles of tires, the state has:

  1. Permitted tire storage facilities
  2. Enforced used tire storage and management laws
  3. Developed recycled tire product options

To find new uses for more than 82 percent of 51 million worn-out tires a year, CalRecycle constantly innovates and evaluates safety studies. The department awards grants and loans to businesses and public entities to expand the safest markets for waste tires.

tire cover on playground

Different styles of playground cover are a common use of recycled tires.

Across California, companies are producing tire-derived products made from recycled tires, including:

  • Playground surfaces
  • Roofing
  • Flooring, including rubber mats for gyms
  • Path cover
  • Roads
  • Accessibility ramps

cars driving on golden gate bridge

Where the rubber becomes the road

For more than 30 years, ground-up, recycled tires mixed with asphalt have produced cost-effective, durable, and environmentally friendly binder in concrete road cover.  Overall, about 2.7 million tires have gone to paving California’s roads.

Tire rubber makes up only about 1 percent of rubberized asphalt concrete. The asphalt binder absorbs the rubber into it, reducing its ability to break away as a microparticle. These streets last about 50 percent longer than roads made from asphalt alone.

tire project

 Many local governments have used tire-derived aggregate in place of conventional construction material for civil engineering projects to:

  • Backfill retaining walls
  • Stabilize hills to keep them from slipping into landslides
  • Absorb vibrations 
  • Fill in land for other reasons

This tire material helps solve a variety of civil engineering challenges because it drains better and costs less than other lightweight, mixed material building aggregate.

“Tire-derived aggregate requires minimum processing and reduces the need for mining (like other lightweight fills) in facilities that generate greenhouse gases,” said William Heung, CalRecycle Senior Waste Management Engineer for the Materials Management and Local Assistance Division.

Tires saved millions on California transportation

Local governments used this tire material to expand rail systems for both the Bay Area Rapid Transportation (BART) and the Metropolitan Transportation Agency in Southern California. The cushioning rubber from tires absorbs vibrations underneath the tracks.

Along with keeping about 500,000 tires from going into landfills, these two projects saved BART and MTA millions of dollars.

tire project aerial shot

Tire material stabilizes a retaining wall on a hill that prevents mudslides in Santa Barbara. 

A recent innovative road project in Santa Barbara used tire material to stabilize a retaining wall located on a hill. Because the tire material won’t degrade even when wet, engineers expect it to support the retaining wall more effectively and help prevent mudslides that can happen when water washes away soil on a hill. (View video.)

Keeping tires from trashing California

California’s population will continue to grow, so our efforts to expand tire recycling must keep pace.

Over the last few years, through its grants and loans, CalRecycle has funded rubberized road concrete and other tire material projects to prevent millions of waste tires from ending up illegally dumped or in landfills.

CalRecycle explores potential tire products as we work to reach the state's zero waste goals while preventing tire fires that pollute our air with poisonous smoke. 

— Syd Fong
Posted on Feb 18, 2020

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Summary: Until 19 years ago, countless illegally dumped tires polluted our state. Large piles of old tires sometimes even caught fire in the hot California sun. These tire fires put off toxic smoke containing cyanide and carbon monoxide. Because a fire can continue to burn deep inside a pile of tires after the top layer appears extinguished, firefighters struggled to put out these smoldering blazes that emitted thick, black plumes of toxic smoke and sometimes burned for months.