This falls under category of a good idea whose time has come. Consider that there are literally millions on vehicles on the road with clip-on or stick-on lead weights that balance the tire and wheel combination. It's a statistical certainty that a percentage of those either fall off or end up in landfills where eventually the lead will pollute the ground water. This idea originated out of California when the Oakland-based Center for Environmental Health won a recent lawsuit against Chrysler and the three largest manufacturers of lead weights in this country to ban their use in California beginning in 2009. Goodyear is also on board with this ban. The lead will be replaced either with steel or zinc alloy weights. Lead is highly toxic and even small amounts can poison thousands of gallons of natural underground water reservoirs.