Abstract: Method and apparatus for enabling automated measurement of both balance and force variation of a pneumatic tire on a single machine. The preferred embodiment modifies a production force variation machine to provide a top spindle housing with mechanically quiet bearings between the housing and a rotatable top spindle; mounts balance measuring sensors on the top spindle housing; provides a variable speed rotational drive motor with a clutch at the top spindle; and provides a mechanically quiet rotary air coupling to interface an air line with a rotatable bottom flange. After loading the tire, the rotatable bottom flange is disconnected from a bottom spindle. For balance measurements, a loading wheel is disengaged from the tire, tire rotation is accelerated to a high speed, and the clutch disconnects the motor which can, if desired, be turned off for balance measurements. The motor is re-connected to decelerate tire rotation.