Sixty percent of the rubber consumed in the United States is used to make tires. Raw materials used to make tires include: rubber (41 percent), carbon black (28 percent), steel (15 percent) and other materials (16 percent).
In 2000, 273 million scrap tires were generated and 321 million new tires were shipped for use by cars and trucks. Of the 273 million, cars supply 84 percent of scrap tires, trucks supply 15 percent and heavy equipment, such as aircraft and off-road vehicles, supply 1 percent. Of the 321 million, 259 million (81 percent) were for cars and 42 million (19 percent) were for trucks. Additionally, 73 million (23 percent) were “original equipment” tires and 248 million (77 percent) were replacement tires for used tires.
Scrap tires present unique recycling and disposal challenges because they are heavy, bulky and made from many materials. The biggest market for scrap tires is tire-derived fuel (TDF), which is a low sulfur, high-heating value fuel.
Scrap tires can be recycled as whole or split tires, or as crumb (ground) or shredded rubber. Whole tire uses include artificial reefs and playground equipment. Split tire uses include floor mats, belts and dock bumpers. Crumb rubber uses include rubber and plastic products, such as mudguards, carpet padding, tracks and athletic surfaces, and rubberized asphalt. Shredded uses include road embankment or roadfill material.
Chaz Miller is director of state programs for the Environmental Industry Associations, Washington, D.C. E-mail the author at: [email protected].
Scrap Tires Municipal Solid Waste (MSW) Facts:
- 4.6 million tons or 2% of generated MSW by weight.*
- One scrap tire is generated per person per year.
- The average weight of a car scrap tire is 20 pounds.
- The average weight of a truck scrap tire is 100 pounds.
- A steel-belted radial passenger tire will have 2.5 pounds of steel.
- 1.2 million tons for a 26.5% recovery rate.*
- 196 million tires in 2000 for a 72% recovery rate, according to industry figures.
- New tires can have a small amount of ground (recycled) rubber.
- Retreads contain 75% recycled content.
Scrap tires do not compost but shredded tire chips can be used as a bulking agent in composting wastewater treatment sludge.
Incinerated or Landfilled:
- 3.42 million tons or 2.1% of discarded MSW by weight.*
- Scrap tires have a 15,000 Btu fuel value per pound, which is slightly higher than coal.
- Unlandfilled scrap tires can create a public health problem as mosquito breeding areas.
- Landfilled single tires can pose problems if the tires fail to compress within the landfill and then rise up and resurface.
- 33 states ban whole tires from landfills.
- 12 states ban all scrap tires from landfills.
- Many landfills use whole or shredded tires as part of the drainage layer over leachate collection systems to improve the system's efficiency. Also, shredded or chipped tires can be used as daily or intermediate cover and to prevent erosion.
Scrap Tire Stockpiles:
- Less than 2,800 scrap tire stockpiles remain in the United States.
- In 2000, approximately 300 million scrap tires were stockpiled, which is a 70% stockpile reduction from 1990.
EPA landfill volume data does not include tires.
- Purchasing longer tread-life tires, rotating and balancing tires every 6,000 miles, and keeping tires at their recommended air pressure levels are the best ways to reduce scrap tires.
- More than 26 million retreaded tires were sold in the United States and Canada in 2000. Most of the retreaded tires are used by trucks. Cars, airplanes and off-road heavy duty vehicles also use retreaded tires.
- Improved manufacturing techniques have doubled the useful life of tires since 1955, with 40,000 mile tires now commonplace.
Scrap Tire Markets:
- In 2000, 498 facilities processed scrap tires.
- TDF is by far the largest market for scrap tires. In 1998, 72 facilities used TDF.
- Using scrap tires to replace other materials used in construction, such as soil, clean fill or drainage aggregate, is the next largest market, followed by ground rubber and exports.
Each market for scrap tires has its own specification.
Recycling Cost and Value:
- Scrap tires usually have low to negative value. In many cases, generators pay a tip fee to scrap tire markets.
- TDF markets are generally linked to the price of coal.
“Municipal Solid Waste in the United States: 1999 Facts and Figures,” EPA, Office of Solid Waste, 2001, Washington, D.C. Website: www.epa.gov/osw
Rubber Manufacturers Association, Washington, D.C. Website: www.rma.org
“Scrap Tire Management Council,” Scrap Tire Use/Disposal Study, 1996 Update,” Scrap Tire Management Council. Website: www.rma.org/scraptires
Tire Retread Information Bureau, Pacific Grove, Calif. Website: www.retread.org
*1999 U.S. EPA estimates.