D. Tire Balancing
Tires should be balanced approximately every 20 000 km, or when drivers feel a
vibration.
A typical tire and wheel assembly weighs about 20 kg (44 lbs.). A difference of as
little as 14 grams (½ oz.) in the distribution of the overall mass of the assembly is
enough to cause a vibration or ìshimmy.î A vibration felt in the steering wheel
suggests that the front wheel is out of balance (has an imbalance), whereas vibration
felt in the driverís seat usually means the rear wheel is out of balance (has an
imbalance).
To balance your wheels, trained professionals use a Dynamic wheel balancer. Small
lead weights are added to the rim to bring the wheel into balance, eliminating both
up-and-down (tramping) movement caused by static imbalance, and side-to-side
(shimmying) movement caused by dynamic imbalance.