During Forcematching, the first harmonic vibration of the tire is matched opposite of 
the first harmonic vibration of the rim to decrease the first harmonic vibration of the 
assembly. This reduces the vibration felt inside of the vehicle. 
A vibration that occurs twice for every revolution is defined as a second harmonic 
vibration. Because there are two vibrations per revolution, the second harmonic 
vibration occurs at twice the frequency of a first harmonic vibration: 
Multiple harmonic vibrations may also occur. For instance, the third order vibration 
causes a three times per revolution vibration: 
Multiple harmonic vibrations may occur at any harmonic factor, dependant only upon 
the number of vibration components in each revolution. 
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 Theory of Operation  GSP9720JLR Wheel Balancer Operation Instructions