Of those, 87.9 percent went to recycling markets, and another 11.2 percent were baled, landfilled or otherwise managed, he said.
“That total of 242.8 million is likely to go up, because vehicle miles traveled (VMT) are going up,” Sheerin said.
The recent annual trend has been for VMT to decrease, but lower fuel prices and the recovery from the recession caused them to rise in 2015, he said.
“Tires last longer, but VMT can overcome that,” he said.
Tire recycling percentages have ranged in the high 80s since 2007, according to Sheerin. The percentage fell to 81 percent in 2011 because of the recession, he said. It rose to nearly 96 percent in 2013, but that was an aberration, he said.
Individual markets have had problems, Sheerin said. Tire-derived fuel, long the mainstay of tire recycling, dropped to 1.92 million tons of utilization in 2015 from a peak of 2.48 million tons in 2007, he said.
“Dedicated tires-to-energy plants are gone,” he said. “They proved uneconomical over time.”
Cement kilns are currently the biggest users of TDF, although there now is a smaller number of large kilns able to burn large numbers of tires, according to Sheerin.
Ground rubber is a strong second among tire recycling markets, though the material peaked in 2009 at 1.35 million tons and hasn't quite recovered from the recession, Sheerin said. Total utilization of ground rubber in 2015 was 1.02 million tons, he said.
Asphalt rubber continues to be a promising market, with Kentucky, Tennessee and Michigan starting to use it, he said. The RMA is co-sponsoring a seminar on asphalt rubber Nov. 2-3 in Ann Arbor, Mich., he said.
As of 2015, there were 67 million stockpiled scrap tires in the U.S., of which 31 million were in Colorado and another 10 million in Texas, Sheerin said.
The figure is approximate, because of the vast differences in the way states calculate the number of stockpiled tires within their borders, Sheerin said. “Some states work diligently to find stockpiled tires, while others claim they don't have any,” he said.
Most end-markets for recycled tire rubber have met resistance from environmentalists and government regulators, according to Sheerin.
“The Holy Grail is taking old tires to make new tires, but most manufacturers are very dubious,” he said.
Currently the biggest challenge to recycled rubber is the controversy over the environmental and health effects of athletic rubber turf, Sheerin said. The RMA is working with the Environmental Protection Agency and the California Office of Environmental Health Hazard Assessment in their multiyear studies of the material, he said.
“We are trying to make sure the agencies have the information they need on what a tire is and what it's made of,” he said.