Wheels and Tires Balancing
The technical definition of balance is the uniform distribution of mass about an axis of rotation, where the center of gravity is in the same location as the center of rotation. A balanced tire is one where mass of the tire'when mounted on its wheel and the car's axle'is uniformly distributed around the axle (its center of rotation). Balanced tires can spell the difference between a positive and negative driving experience.
Sources of Imbalance
Sources of imbalance could be:
- Heavy or light spots in the tire and radial or lateral run-out.
- Variations within the wheel, such as thickness and welds.
- Rotor and axle imbalances.
Heavy or Light Spot Balancing
There are two types of imbalance caused by heavy or light spots: static and dynamic.
- Static imbalance: Occurs when there is a heavy or light spot in the tire so that the tire won't roll evenly and the tire/wheel assembly undergoes an up-and-down movement.
Static balance is achieved with a bubble balancer but does not correct for dynamic imbalance.
- Dynamic imbalance: Occurs when there is unequal weight on both sides of the tire & wheel assembly's circumferential centerline. The tire/wheel assembly has a side-to-side movement.
Dynamic balance is achieved with a spin balancer where the tire & wheel assembly is balanced both statically and dynamically.
- Radial or Run-out Balancing
Depends on whether it is radial or lateral run-out.