Have you ever wandered what happens to rubber when it wears off tires?

By the time the average passenger car tire ends up at the scrap yard, it weighs six pounds less than when it was new. Multiply six pounds by the number of tires scrapped each year in the U.S., and we're talking over three-quarters of million tons of rubber that perform a disappearing act every year!

Most of this rubber wears off tires by abrasion on concrete or asphalt, creating a telltale black smear on the road. A little rubber becomes chemically incorporated into asphalt roads, because asphalt and rubber both are made of petroleum oils. But the vast majority wears off as small particles that are rinsed off the road by rain, or blown off by wind, ending up in the soil, on plants, and in lakes, rivers and streams. We even breathe in rubber particles from the air.

Here's an experiment. Run a rag or tissue across the hood of a car. You're likely to see black soot. Compare its color to the soil in your area--that ain't just garden dirt! Some of the soot is a byproduct of incomplete combustion of fuel in engines, and some is rubber worn off tires.

In order to decrease the amount of pollution caused by tire rubber, keep your tires properly inflated. Over- and under-inflated tires wear down faster, increasing the amount of tire pollution.