Wheel balancing is the process of reducing to an acceptable level the imbalance of the wheel , disc , hub , wheel mounting and suspension elements.
The need for vehicle wheel balancing
In almost 100% of cases, the center of mass of the wheel does not coincide with the geometric center. Accordingly, such a wheel when driving causes increased vibration of the vehicle, which leads to a decrease in comfort (shaking, noise) and to wear of the steering and wheel suspension elements, which increases tire wear . The meaning of static balancing is to “move” the center of mass to the geometric center.
The inner and outer half of the wheel (especially wide-profile) can be considered separately. These parts have their centers of mass, which are not necessarily located on the axis of rotation, even after statistical balancing of the wheel as a whole. The wheel tends to rotate around the axis connecting these points, which leads to an increased load on the bearing and increases wear, especially at high speed. For automobile wheels, dynamic balancing is sufficient only in two planes. For long shafts, such as turbines, balancing is performed for more planes.
Wheel static balance
The static balance of the wheels is a uniform distribution of mass around the circumference of the wheel. For static imbalance assemblies, a vertical vibration , called a wheel jump, occurs. The result of this ultimately can be uneven wheel wear , and most importantly, the level of comfort is significantly reduced, especially when driving at high speed.
For balancing the wheels of passenger cars, trucks and motorcycles, a balancing machine is used to determine the places on the rim to which weights should be added. As a balancing weight, various types of special weights made of lead or zinc are used , which are mounted on the wheel disk outside and inside. This method allows you to balance only the disk assembly with the tire .
It is worth noting that attempts to pour water into the tire, as well as pouring in various loose substances, are not effective for the purpose of “automatic” balancing and do not lead to anything good. Water was poured into the old diagonal tires of the 30s – 40s by athletes who exploited them at speeds far exceeding those used for tires of that time, which led to overheating of the rubber due to internal friction and separation of the sidewall with subsequent destruction. Water allowed the tire to cool somewhat, increasing its speed capabilities. After the appearance of normal high-speed tires, this practice is a thing of the past, but it managed to generate the legend of the miraculous properties of water poured into the chamber, among which was the ability to “automatically” ensure perfect balancing. This misconception has been repeatedly debunked in the automotive literature: if there are "cones" on rubber, a balancing compound or the same water simply accumulates at a point that is furthest from the axis of rotation, adding its mass to the imbalance already formed.