Pitch – The physical quality of sound that relates to the frequency of the wave.
Radial Force Variation (RFV) – A measurement of the tire’s uniformity, under load, in regards to the variation of the load acting towards the center of the tire; commonly referred to as the tire’s sidewall variation.
Radial Run out – A condition where a rotating component does not rotate in a true plane. The component moves up and down on its rotational axis.
Resonance – The tendency of a system to respond increasingly to a compelling force oscillating at, or near, the natural frequency of the system. This causes a sudden and large vibration.
Road Noise – A noise that occurs while driving on gravel or roughly paved roads at all vehicle speeds, or when a vehicle is coasting.
Shake, Lateral – A side-to-side vibration of the body, seats, and steering wheel.
Shake, Vertical – An up and down vibration of the body, seats, and steering wheel.
Shimmy, High-Speed – A vibration that causes the steering wheel to oscillate when driving on smooth roads at high speeds.
Shimmy, Low-Speed – A vibration that causes the steering wheel to oscillate when driving across a bump at low speeds.
Source Component – The component that is diagnosed as being the root cause of a vibration or noise concern.
Sound – The result of a vibrating disturbance of an object, which produces waves that transmit out from the source.
Static Balance – The method of balancing a tire and wheel assembly in a single plane. Static balancing removes only the lateral (side to side, wobble) imbalance and the tire and wheel assembly could possibly have a radial (up and down) vibration.
Torque Sensitive Vibration or Noise – A vibration or noise that is sensitive to different loads and torque, applied to the drive train of a vehicle. The vibration or noise changes when the throttle position or transmission gearing is used, during a road test, to change the torque applied to the drive train.
Vibration – The repetitive motion of an object, back and forth or up and down, which may be felt or heard.
Wheel Diameter – The dimension of a wheel measured on the inside of the wheel at the bead seat area.