Re: Where does all the rubber go that wears off tires?

Tires are made from petroleum hydrocarbons. About 60% of the rubber from tires in the United States is burned for energy as "Tire Derived Fuel". About 20% is divided between export (6%), ground rubber products (5%), civil engineering projects such as fill (4%), stamped rubber products (3%), and agricultural and miscellaneous reuse (2%).

That leaves about 20% of every tire that is lost during the useful life of the tire. The average new passenger car tire weighs about 26 pounds. The average scrap passenger car tire weighs about 20 pounds. In the United States today, we generate about 260 million scrap tires per year. So where does 780,000 tons of rubber go every year?

The short answer is to the road surface. A very small amount volatalizes directly to the air (sometimes called dry rot), but this is insignificant compared to the rubber that is ground from the tread by the abrasive action of the pavement. A small amount is incorporated in the asphalt itself. Remember that the asphalt and tire are both made from petroleum oils. Sadly, the bulk of the 3/4 million ton of rubber each year ends up in the land and surface waters. It starts out as a black stain on the road, but is quickly washed by rain to rivers, lakes and streams; or blown by wind or traffic into the air. Once in the air, it can be inhaled by humans and wildlife or it can settle on plant, water, and soil surfaces.

I'll bet that if you go out right now and swipe a clean facial tissue across the hood of the family car, you'll find something much darker than the local soil. Some of that black soot is from the incomplete combustion of petroleum fuels in car and truck engines. But some of it was once part of a tire.