Lead wheel weights are sinking under new rules and new technology.
The goal of eliminating lead wheel weights is an outgrowth of regulations enacted in Europe in September of 2000. Called the ELV Directive (2000/53/EC), these regulations are aimed at "reduction and control of hazardous substances in vehicles, in order to prevent their release into the environment." The directive is focused on reducing the environmental impact of motor vehicles at the end of their service life by, among other things, eliminating certain materials used to build the vehicle. "In particular, the use of lead (and other heavy metals) should be prohibited."
Although lead constitutes only about 4 percent (by weight) of the average vehicle, its significant impact on human health makes it a primary target of the directive. But the regulators took a realistic approach. Planned revisions to the regulations in 2003 exempted certain parts made with lead alloys, like engine bearings, because they can't be recovered economically. While lead battery clamps are banned, lead-acid batteries are exempt until there is a better alternative, and also because battery lead is relatively easy to recover during vehicle salvage. But lead wheel weights are a different matter. They're easy enough to recover, but only if they make it to the salvage yard.Here in the U.S., an oft-cited peer-reviewed study published in 2000 by Robert Root, a senior research scientist (retired) from the Battelle Memorial Institute, found that lead pollution from wheel weights "is continuous, significant, and widespread, and is potentially a major source of human lead exposure." His research indicated that lead wheel weights dropped on city streets are quickly ground into tiny particles that are easily washed into storm drains and then into local water supplies. His measurements showed that one year of lead accumulation at one specific intersection in his home town "would exceed the federal lead hazard guidelines by more than 10,000 times."
A report published by the U.S. Geological Survey in 2006 estimates there was about 65,000 tons of lead wheel weights in use in this country in 2003. Most of that lead was on vehicles, but about 18,000 tons of weights were in service shops ready for installation. About 3,000 tons of weights was recovered at salvage yards. But the important figure is the amount of lead wheel weights estimated to be lost on U.S. roads that year: about 2,000 tons. Two thousand tons a year may not seem like a large number, especially when compared to the annual release of other known hazardous materials. But Root's conclusions about how the lead in wheel weights enters populated environments has had a major effect on the issue.The European Union banned lead wheel weights as original equipment in 2003 and banned them from the aftermarket in 2005. The Japanese government asked its auto industry to reduce its use of lead, so Japanese and Korean manufacturers voluntarily stopped using lead wheel weights by 2005. There are no federal regulations here in the United States, but the EPA has launched a voluntary National Lead-Free Wheel Weight Initiative. In addition, non-government environmental groups are taking legal action in several states, hoping to convince them to ban lead wheel weights. Their efforts bore fruit earlier this year in California.
Who's doing what
In September 2008, California's Center for Environmental Health (CEH) reached "a legal agreement" with Chrysler and three large wheel weight producers, requiring the companies to stop shipping lead wheel weights into the state by the end of 2009. While Chrysler is probably the last carmaker to switch to non-leaded wheel weights for any of its new cars, it is now phasing out the use of lead in 55 percent of the vehicles shipped to California. Chrysler reports it will fully eliminate lead weights by August 2009 from cars intended for sale in California.
Three large wheel weight suppliers — Plombco, Hennessey and Perfect Equipment — have agreed to stop shipping lead weights to California service shops by the time the ban takes effect next year. Perfect Equipment says it has the most comprehensive line of lead-free wheel weights in the industry. Plombco is the first North American producer to offer lead-free wheel weights to OEMs and to the aftermarket. BADA, a division of Hennessy, has launched a Web site (www.steelwheelweights.com) aimed at promoting the environmental benefits of its line of steel wheel weights.
The state governments of Washington, Maine and Massachusetts are considering lead weight bans, and Maine and Minnesota already have eliminated lead weights from their state vehicles. The U.S. Air Force and the U.S. Postal Service are also gradually eliminating lead weights from their motor pools.
In late 2007, Bridgestone Firestone announced plans to require all its service stores to switch to steel weights. Their outlets include Firestone Complete Auto Care, Tires Plus, ExpertTire and Wheel Works.
GM has voluntarily stopped using lead weights in most of its models from Chevrolet, Cadillac, Buick, Pontiac and Saturn, and in all Saab models. So far, Ford is using non-lead weights on only one model, but that is expected to change soon. Chrysler has announced plans to eliminate lead wheel weights by 2011.
The alternatives
Non-lead wheel weights are either steel or zinc, and as a substitute for the technology we've been using for the last 70 years, each presents its own challenges. First of all, both materials are lighter than lead so the weights have to be larger: about 10 percent for steel weights, and about 20 percent for zinc. While this is not a problem on most wheel balance jobs, wheels that need lots of extra weight will have the added weight spread over a wider area. This can change the wheel's center of mass, making the overall job more difficult and time-consuming.
Zinc is a bit more expensive then lead, but it's already used in the auto industry in various alloys and as electroplate coating. Steel is heavier and less expensive than zinc, but it corrodes easily, especially in the presence of salt.
Both steel and zinc will chemically react with other metals more easily than lead. Any place dissimilar metals touch each other, there is a possibility of corrosion, and in this application the wheel is more likely to suffer. Lead wheel weights have been available with a polymer (plastic) coating since the 1980s to protect aluminum wheels from corrosion. Today's non-lead weights are coated even for use on steel wheels, and that adds to the price. Also, some people recommend against reusing coated weights because the coating may be damaged.
In Europe, they're using zinc wheel weights almost exclusively. Most Asian vehicles are also fitted with zinc weights, but several have steel weights. GM uses both, but the zinc weights are only on their European imports (Saab and Saturn). It looks like Ford (and now Chrysler) will use steel. The aftermarket offers both, plus a steel/polymer "composite" stick-on weight available on a roll that is cut to size during installation.
Saving weight
In addition to using non-lead wheel weights, the car manufacturers have also found a way to balance wheels with less added weight.
Computerized wheel balancers detect force, not weight, because they spin the wheel to detect imbalance. The force radiates out from a single point in space, the center of the wheel hub, and the computer knows where that point is. Using the machine's sensor arm, the tech tells the computer where, in relation to that center point, the weight can be applied. Now the computer can determine how much weight is needed to balance the forces.
The computer is programmed to balance the forces on either side of the center point and parallel to the wheel's plane of rotation, and in an intersecting plane parallel to the wheel's axis of rotation. A heavy spot on one side of the center point makes the wheel wobble or shimmy as it spins, and it's called the "couple balance." The same heavy spot is also some distance from the axis of rotation, making the wheel hop as the heavy spot rolls up off the ground. That's called "static balance." Once the computer knows the wheel dimensions and imbalance forces at a specific rpm, it can calculate the weight and location that will provide the best possible couple and static balance around the center of the hub at any rpm. That's the important point here: the computer seeks the best balance of both forces.
The automakers have learned that the best possible couple balance is not necessary. Suspension systems are designed to move in the static balance plane, so it's easier for the wheel to hop in that plane. When the wheel tries to wobble due to couple imbalance, there's more than just the spring and shock absorber to resist that movement. So instead of trying to resolve as much imbalance as possible in both planes, the car manufacturers have learned that they can tolerate some couple imbalance if that allows a more precise static balance. They've programmed their own wheel balance machines to operate that way, and the benefit is more than just a smoother ride. They've also learned that balancing a wheel this way almost always requires less weight, and the weight savings in dollars is significant.
So far, the only aftermarket balancing software with this feature is Hunter Engineering's SmartWeight, which allows the technician to choose the between "traditional" and "WeightSaver" balancing methods. The software was developed to achieve a smoother ride and therefore fewer come-backs for the shop, but users also report needing significantly less weight to balance wheels. This has been noted by the lead-free-weight community.
Equipment
The best wheel balancer in the world is only as good as its calibration. Some equipment manufacturers recommend calibrating the machine after balancing 100 wheels. Some users say that because computer-based balancers can self-calibrate in minutes, it should be done daily just to account for changes in the weather. Either way, it's a relatively quick and foolproof task to calibrate the electronics, but that's only part of the job. According to a service bulletin from Yokohama Tire, a wheel balancer should be able to repeat a reading to within 1/8 of an ounce (3.5 grams). Most computerized machines are accurate down to 2 grams, but repeatability is more often a matter of operator skill.
The machine's repeatability is easy to check: simply rotate the wheel on the spindle and see if the machine calls for the same weights and locations. It doesn't matter whether the wheel/tire assembly is balanced, only that the machine produces the same numbers every time. If the readings don't repeat within a few grams and a few degrees, the wheel is not spinning in the same plane. This could be because it's not being mounted properly on the machine, or because something is mechanically unsound. It's time for a little investigation.
The first thing to check is the wheel and tire being used for this test. The wheel must be straight and the center hole must be round and undamaged. Balancing machines with a manual rim size sensor also have software that uses the sensor as a dial indicator for checking the wheel with the tire removed. Also, the tire must not have any water, excess mounting lube, flat-fix or dynamic balancing beads inside. Some shops keep a known-good wheel/tire assembly that's used just for this purpose.
With these conditions met, the next thing to check is the cone and spindle. The cone must fit properly on the spindle, and the spindle must be in good condition and securely mounted in the machine. These parts can wear, and replacement spindles and cones are available for most machines.
The cone must also be sized correctly for the wheel. A cone that's too large to fit the hub hole is obvious, but it's not always obvious if the cone is too small. One company, Haweka (which does not make wheel balancers but does produce an extensive line of wheel balancer accessories), offers an expanding collett for use in place of the cone, assuring the right fit in every wheel.
Some light truck wheels and many aftermarket wheels center on the lug nut holes, not the hub. Even if the hub is still the true center of the wheel, that's not how the wheel will be centered on the vehicle. The only way to balance that wheel properly is to mount it on the machine with a flange plate. Rather than require a bewildering assortment of different size flange plates, some manufacturers offer a universal plate with studs that can be moved to the necessary locations.
One final item that's easy to overlook is the electrical supply to the balance machine. That machine contains a computer, and while it is designed for the shop environment, it's still a good idea to power it from a circuit that doesn't also power the compressor or other large motors.
Lead wheel weights will remain available for the foreseeable future simply because there are so many of them out there. But the reasons for eliminating them are valid, and on a wheel-for-wheel basis, the alternatives aren't expensive. To prepare for a movement that may become law some day, contact your wheel weight supplier and explore the alternatives. Information is also available at www.leadfreewheels.org, www.cehca.org, www.epa.gov and ec.europa.eu.
