Materials Management - Waste Tires
Industry experts estimate that waste tires (also known as scrap tires) are generated at a rate of about one tire per person per year. Using recent census data for the northeast, NEWMOA estimates that the number of waste tires produced in the northeast is approximately 43.3 million per year (based on the 2018 census). Although today’s tires last for more miles than they did in the past, the number of cars on the road is increasing, and the average number of miles driven annually is also increasing.
A relatively small percentage of the tires received at an automotive recycler can be reused or retreaded. The vast majority of the tires are waste tires and need to be either recycled or disposed of. Recycling is the preferred option. Waste tires can be used as fuel (tire-derived fuel or TDF) as well as in a variety of civil engineering applications in landfills and highways, and at playgrounds, horse arenas, and running tracks. Tires have good engineering properties and can be used as:
- Road building material, chiefly as an additive or supplement to asphalt
- Engineering applications, such as lightweight fill to support road base material and as fill behind retaining walls
- Drainage material in landfills and leachate systems in septic system design
- Paving material to occupy the space between and around railroad tracks
- Rubber matting for playground surfaces and in and as surfacing for equestrian arena
Generally, waste tires are shredded before they are recycled. Shredding reduces the volume of tires, eliminates the compaction problem at landfills, and eliminates mosquito-breeding locations. Approximately 730,000 tons of tires are recycled per year in the US, which is about a 19 percent recovery rate. New tires contain no more than 2 percent recycled rubber. Retreads contain 75 percent recycled content.
Some facilities have collected large quantities of tires that they stockpile believing that they will one day find a lucrative market for them. Stockpiling is not a disposal option, and speculative accumulation of tires is most likely to result in high costs. Stockpiles of waste tires can cause safety and health problems. Although tires are difficult to ignite, once they are lit the fire is almost impossible to extinguish. Fumes from burning tires can affect nearby residents and firefighters in a variety of short- and long-term ways, ranging from irritation of the skin, eyes, and mucous membranes; central nervous system effects; depression; respiratory effects; and cancer. Fire also melts the rubber in tires and generates oil (called “pyrolytic oil”) that can pollute the ground and surface water. Concentrations of metals (such as iron, zinc, tin and aluminum) in the ash residue from tire fires may be high, and they can contaminate surface and ground water if not properly handled. Therefore, these residues are often classified as hazardous wastes. Cleanup of tire fire sites is frequently difficult and expensive. Furthermore, rainwater collected inside stockpiled tires provides a breeding ground for mosquitoes, which transmit illnesses, including West Nile virus and encephalitis. The number of waste tires stockpiled in the U.S., plus the number being generated each year, exceeds the recycling market demand.
Most states restrict tire disposal at landfills. Landfilled tires consume valuable capacity and may result in an unstable base for constructing the landfill cap. Landfilling tires can pose problems if the tires fail to compress within the landfill then rise up and resurface. As with tire piles, landfilled scrap tires can create a public health problem as mosquito breeding areas.
NEWMOA has prepared several reports on waste tires to help state programs improve the management of this waste stream, including:
- Review of Northeast States’ Tire Programs [PDF] 2020. 26 pp.
- Northeast End Markets Tire Waste Paper [PDF] 2019. 3 pp.
- Waste Tires in the NEWMOA States [PDF] 2002. 26 pp.