Wheel weights are small pieces of metal used to correct weight imbalances on automotive wheels and tires. Most modern wheel weights are made of zinc, and they typically clip onto the outer edge of wheel's rim. However, some wheels require sticking wheel weights directly onto the rim.
Wheel weights extend the life of a tire and improve the passengers' ride quality by ensuring that the wheel has proper weight distribution. When a wheel's weight is not properly distributed, the wheel wobbles slightly when the vehicle travels at speed. When the wheel wobbles, it moves stress from the reinforced center of the tire's tread to its weaker outer edges, greatly reducing the tire's service life. In serious imbalances, the wobble becomes so extreme that the entire vehicle shakes or vibrates while in motion.
Most wheels only require standard, clip-on wheel weights. However, clip-on wheel weights can cause scratches or scrapes where they attach to the wheel. Expensive wheels made of magnesium or chrome alloys use adhesive wheel weights which do not affect the wheel's finish. Both types of wheel weights require monitoring, as they can easily fall off the wheel, creating new imbalances.
Wheel weights in the past featured construction using lead, which introduced large quantities of the toxic metal into the environment. Modern wheel weights use zinc instead of lead, which is gentler on the environment.