Rubber is recyclable, but not in the way most people expect. You can’t toss a rubber item into your curbside recycling bin and have it melted down like a plastic bottle or aluminum can. The chemical structure of most rubber products makes them impossible to simply melt and reshape. Instead, rubber recycling relies on specialized processes like grinding, chemical treatment, or energy recovery. Tires, which represent the vast majority of rubber waste, have a recycling rate of about 79% in the U.S., up from just 11% in 1990.
Why Rubber Is Hard to Recycle
Almost all rubber products you encounter, from tires to shoe soles to yoga mats, have gone through a manufacturing step called vulcanization. During this process, sulfur or similar chemicals create permanent bonds between the rubber’s long molecular chains, locking them into a rigid three-dimensional network. This is what gives rubber its bounce, strength, and heat resistance.
The trade-off is that these bonds are irreversible. Unlike plastics such as water bottles or milk jugs, which can be melted and reshaped, vulcanized rubber is what engineers call a thermoset material. It won’t soften when heated. It can’t be dissolved in a solvent and reformed. This applies equally to natural rubber (harvested from trees) and synthetic rubber (made from petroleum). Once vulcanized, both types face the same recycling barrier.
How Rubber Actually Gets Recycled
Since you can’t melt rubber down, recyclers use other approaches. The most common is mechanical grinding: shredding rubber into small pieces or fine crumbs, then using those particles as a raw material in new products. Ground tire rubber, often called “crumb rubber,” shows up in playground surfaces, running tracks, synthetic turf infill, rubberized asphalt for roads, and landscaping mulch. This isn’t recycling in the closed-loop sense (old tires becoming new tires) but it does keep the material out of landfills.
A more advanced approach is devulcanization, which attempts to reverse the chemical bonding that makes rubber so stubborn. Researchers have tested dozens of methods, including high heat combined with chemical agents, microwave energy that targets and breaks sulfur bonds, ultrasonic vibration, and even bacteria and fungi that slowly digest the sulfur crosslinks. Microwave devulcanization has shown the most dramatic results in lab settings, achieving up to 82% reversal of the crosslinking. Biological methods, where microorganisms break down the sulfur bonds, work only on the surface of rubber particles and manage to remove less than 5% of the sulfur over a 40-day period.
The method considered most practical for large-scale operations is thermomechanical devulcanization using industrial extruders, essentially combining intense heat, pressure, and shearing force to partially break apart the rubber’s internal structure. The resulting material isn’t as strong as virgin rubber, but it can be blended into new rubber products to reduce the need for fresh raw materials.
What Happens to Old Tires
Tires are by far the largest source of recyclable rubber. According to the U.S. Tire Manufacturers Association, roughly 79% of end-of-life tires now go to recycling or reclaiming markets. The biggest single use is tire-derived fuel: cement kilns, paper mills, and power plants burn shredded tires as an energy source, since rubber has a higher energy content per pound than coal. Ground rubber for products like asphalt and sports surfaces accounts for another significant share. A smaller portion is retreaded (resurfaced for reuse on trucks) or exported.
The remaining 21% still ends up in landfills or stockpiles. Whole tires are particularly problematic in landfills because they trap air and tend to rise to the surface over time, damaging landfill caps. A rubber boot sole takes an estimated 50 to 80 years to decompose. Vulcanized tire rubber, which is denser and more chemically stable, lasts far longer.
Natural Rubber Does Biodegrade, Slowly
Natural rubber, the kind harvested from rubber trees, will eventually break down in the environment. Soil microorganisms, particularly certain fungi, can digest the polymer chains over time. The process requires oxygen, moisture, and microbial activity, and it moves through stages: first the surface deteriorates, then microbes fragment the material, then they absorb and metabolize the fragments, and finally the rubber converts to carbon dioxide and water.
This sounds promising, but the rates are slow compared to other natural materials like wood or cotton. Natural rubber’s branched molecular structure makes it resistant to microbial attack. And most rubber products aren’t pure natural rubber. They contain synthetic rubber blends, fillers like carbon black, and chemical additives that further slow or prevent biodegradation. A natural rubber band left in a garden will eventually crumble. A tire sitting in a field will not, at least not within a human lifetime.
Recycling Rubber at Home
Your curbside recycling program almost certainly does not accept rubber of any kind. Rubber items contaminate the recycling stream for plastics, paper, and metals, so throwing them in the bin does more harm than good.
For tires, most tire retailers accept old tires when you buy new ones, often for a small disposal fee. Many municipalities also hold periodic tire collection events or accept them at designated drop-off sites.
For smaller items like yoga mats, shoes, and rubber household goods, options are more limited but growing. TerraCycle offers a paid recycling box program for sporting goods including yoga mats. Some mat manufacturers run take-back programs: LovEarth in Australia provides return shipping labels, and BeJollie offers free recycling for customers who buy a new mat. Nike’s Reuse-A-Shoe program accepts worn-out athletic shoes of any brand at Nike retail locations and grinds them into material for sports surfaces.
For rubber items with no clear recycling path, your best option is to check with your local waste management agency. Some accept rubber in bulky waste pickups. Others direct you to specialty recyclers. Items in usable condition, like rubber boots or exercise equipment, can often be donated rather than discarded.
Crumb Rubber Safety Concerns
One issue worth knowing about: the crumb rubber used in synthetic turf fields and playgrounds has raised health questions. Recycled tire rubber contains a mix of chemicals, and children playing on these surfaces may be exposed through skin contact, inhalation of particles, or accidentally swallowing small crumbs. The National Institute of Environmental Health Sciences has studied the issue and found no clear evidence of increased health risk, but has noted that additional research, particularly on long-term inhalation of certain compounds, is still needed. This remains an active area of investigation rather than a settled question.