Scientific American: Few consumer products have a poorer environmental image than the car tire. It is hard to escape the bleak sight of coal-colored mountains of used tires that blight the U.S. landscape. But like other parts of the automobile, the tire has been partially reworked during the past decade to make it more ecologically sustainable. As a result of efforts by tire industry chemists and engineers, many of today’s tires roll more easily to save fuel and contain fewer petroleum-based ingredients, both of …