Wheel weights are clipped to the rims of every automobile wheel in the United States in order to balance the tires. These weights often come loose and fall off. They are either washed into storm sewers and end up in waterways or are gathered during street cleaning and placed in municipal landfills. Under the NLFWWI EPA is encourageing the phase-out of the sale and installation of lead wheel weights. The U.S. Air Force, Postal Service, and General Services Administration have joined this initiative.