Tire balance, also referred to as tire unbalance or imbalance, describes the distribution of mass within an automobile tire or the wheel to which it is attached.
When the tire rotates, asymmetries of mass cause the wheel to wobble, which can cause ride disturbances, usually vertical and lateral vibrations.
It can also result in a wobbling of the steering. The ride disturbance due to unbalance usually increases with speed. Vehicle suspensions can be excited
by tire unbalance forces when the speed of the wheel reaches a point that its rotating frequency equals the suspension’s resonant frequency.
Tires are inspected in factories and repair shops by two methods: static balancers and dynamic balancers. Tires with high unbalance forces are downgraded
or rejected. When tires are fitted to wheels at the point of sale, they are measured again, and correction weights are applied to counteract the combined effect
of the tire and wheel unbalance. After sale, tires may be rebalanced if driver perceives excessive vibration.