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Q & A: Wheel Balancing

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Most recent answer: 10/22/2007
Q:
What do drivers mean when they say that the car needs wheel balancing?
- Anonymous (age 20)
University of Baguio, Philippines
A:
They mean that the weight isnít distributed evenly around the tire. Imagine you put a little extra weight on one part of the tire. As that swings around, the total momentum of the tire keeps changing direction. That means the axle has to keep exerting a force on the tire. The force thatís needed keeps changing direction as the tire goes around in circles.  That force, constantly changing direction, causes vibrations in the rest of the car -- it causes unnecessary stress on the bearings and can rattle pieces of the car. Nuts and bolts can become unscrewed over long periods of time when exposed to vibration. Drivers and passengers may feel the vibration when the car is in motion.

The standard way to test the balance is to put the tire on a flexible axle and give it a spin. If the axle wobbles, the tire is out of balance. The standard way to balance them is by clipping little extra weights on.

Mike W. (and Tom)

(published on 10/22/2007)

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