[jspatz1]

A servo is the proper motor for this positioning job (as it is for most robot motions), and is what one would use in an FRC robot if one could. When FRC robots use a gearmotor and feedback pot/encoder to do positioning in FRC, we are doing what some would call a "poor man's servo," but a real one would be superior. As mentioned already, make sure you size the servo with sufficient torque to do the steering job at the rotational speed you desire. Consider all the accumulated friction in your system, and the torque required when the robot is stationary and the wheels are loaded on a high-friction surface.