The voltage rating specify which constant voltage will, after a bit of time, generate the rated current.
For motors that move, this isn't very useful. As long as you have a controller that lets you limit the current (typically, a chopping controller,) you want the voltage to be as high as your controller will let you; this lets your controller drive the current up to the desired value as fast as possible, to overcome the inductance of the windings in the motor.