Very often we come across the term `balancing`when we refer to tires for our vehicle. Ever wondered what this technical term means and how `balancing` is achieved?
In this article, let us take a close look at what is `balancing` and why do tires need to be balanced and how it is achieved for optimum performance.
Static and dynamic balance
Any rotating mass that is pivoted in the center has to have perfect static and dynamic balance in order for the mass to rotate without any wobble or hop. Due to uneven mass distribution during the manufacturing process, heavy spots can occur as in the illustration. When the mass is rotated at higher speeds, static or dynamic imbalance will result in vertical or lateral vibration.
Relating the above condition to a tire fitted to a rim, the distribution of mass within the tire/rim assembly must be uniform for this assembly to rotate without any vertical or lateral vibration. It is important for this balance to be achieved for a comfortable drive and uniform tire wear throughout the lifespan of a set of tires.
Balancing procedure and machine
In order to achieve static and dynamic balance of a tire/rim assembly when rotated, weights are put on to the wheel rim in specific locations to balance the asymmetric mass which must be evenly distributed throughout the tire/rim assembly. Modern day wheel balancing machines measure and correct both static and dynamic imbalance. The tire/rim assembly is rotated at speeds of 300 revolutions per minute or higher and sensors measure the forces of imbalance. The machine identifies the exact spot and size of weight to be used.
As part of a tire maintenance schedule, balancing all the tires of a vehicle at periodic intervals (every 10,000 km) should be practiced without fail. During the course of operation of a set of tires, tire balance can run out. Periodic tire balancing must be carried out in order to correct the unbalance which if left unchecked, will result in uneven wear and damage to the tires. The vibration caused by an unbalanced wheel will also damage the adjoining steering and suspension parts in the long run. An experienced driver will be able to notice an uncomfortable steering vibration also known as steering `shimmy` especially when the front wheels are unbalanced. It is always advisable to carry out periodic balancing instead of waiting for signs of wheel unbalance to show up which may result in expensive steering parts replacement.
Generally there are two types of balancing weights commonly used on car tire/rim assembly. As indicated in our illustration, they are the clip-on type and the adhesive paste-on type. Depending on the rim construction, both types are used widely for tire/rim balancing. Needles to say that the clip-on type can only be used on rims that have a circumference lip as in the illustration. And the adhesive type wheel weights are usually used on the inside of any present day wheel rim as it fits snugly without obstructing any brake parts during the rotation of the wheel.
Present day wheel weights are made of a zinc alloy or coated steel. They have replaced lead weights to suit the finishing of styled wheel rims used by most manufacturers. Lead wheel weights used to be popular in the early years but discontinued due to environmental regulations.
From the facts gathered on` why do tires need to be balanced`, tires indeed need to be balanced on a periodic basis to maintain a comfortable and smooth drive, to attain a good life span of the set of tires and to avoid any costly, premature replacement of any steering and suspension parts.
Should there be a concern or a question that you would like to raise, I would be most happy to communicate for a better understanding on the topic of tire balancing.