Tire Balancing Explained

Keeping Your Tires Balanced Is An Important Part of Regular Tire Maintenance.

The weight of a tire must be properly balanced or a variety of problems can occur. A review of tire patent documentation from the 1940s reveals that tire manufacturers were concerned with the fact that almost every tire made differed slightly from all others. Naturally, this manufacturing inconsistency created difficulties for the tire service industry. As cars became more popular and the number of tires being sold increased to keep pace, these difficulties multiplied until they became a major issue for the companies servicing the tires.

In addition to tire degradation over time, potential problems that can be caused by one or more out-of-balance tires include a rough ride that’s often accompanied by vibration, wobbling or shaking. Unbalanced tires can also wear unevenly, reducing their useful life and causing owners to incur premature tire replacement expenses. Even worse, a major investigation conducted by the Army Materials and Mechanics Research Center (U.S.) determined that out-of-balance tires can result in higher operating temperatures which in turn can exacerbate existing tire defects and make them more dangerous!

A tire is balanced by positioning weights on the wheel on which the tire is mounted. These weights act as a counterbalance to heavy spots on the tire/wheel assembly. The process of balancing a tire requires special equipment and should always be performed by a qualified service technician.

Unfortunately, the historic lack of uniformity in tire manufacturing continues even today. As a result of these continuing manufacturing inconsistencies, tires still must be balanced before they can be used on a vehicle safely. A vehicle with properly aligned wheels and balanced tires can compensate for some problems introduced by poorly designed tires with irregular geometry and/or poorly manufactured tires which exhibit quality control issues. With properly balanced tires, a vehicle will have a smoother ride and be safer to drive because some existing manufacturing and/or design defects will be counterbalanced. Tire replacement costs will also be lower because premature wear will be reduced or prevented.

Furthermore, keeping a vehicle’s tires properly balanced can forestall certain issues in the event a tire failure results in injuries and litigation. As part of its defense during such litigation, the tire manufacturer will wish to deflect fault away from itself and any design and/or manufacturing defects of the failed tire. It will try to cast blame for the tire failure on the owner’s failure to keep the tire in proper balance and the resulting uneven wear. The tire manufacturer will not be able to use this strategy during its defense (at least not successfully) if the tire was properly balanced the entire time it was in use.

It’s important to keep in mind that the tires on smaller cars may need to be balanced more often than those on larger vehicles. Alignment and/or balance problems are exaggerated on small cars simply because they weigh less and consequently are less able to smooth out these problems.

One final important note, this time directed to tire service centers: DO NOT install a new tire on a vehicle if it seems unusually difficult to balance. The tire may have a serious uniformity problem caused by a manufacturing defect which may not be readily apparent.

Sources:
U.S. Patent Number 2242430, Sept. 7, 1939

A Temperature Study of Pneumatic Tires During Highway Operation, Army Materials and Mechanics Research Center, December 1972.  Available online at:  http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD755817

http://www.safercar.gov/Vehicle+Shoppers/Tires/Tires+Rating/Balance+&+Alignment

M. G. Pottinger (2010) Uniformity: A Crucial Attribute of Tire/Wheel Assemblies. Tire Science and Technology: March 2010, Vol. 38, No. 1, pp. 24-46.