When wheels are correctly balanced it minimizes vibrations from the wheels. The vibrations happen because the wheel / tyre can have heavy spots caused by slight imperfections. By placing wheel weights in specific places it smoothes out the vibrations that would be caused.
Wheels are balanced on a wheel balancing machine. This machines spins the wheel and tyre once they have been mounted together and inflated, then automatically calculates the amount of weight and location of the weight that needs to be attached to the wheel.
You can sometimes notice balancing problems because the steering wheel will start to shake at high speeds (normally around 50 � 70 mph). However this is not always the case, if your rear wheels are out of balance you may not feel it, but wheels which are not balanced correctly can cause wearing of suspension and steering parts. We recommend that all vehicle wheels are balanced and checked periodically.