The present invention provides an enhanced method and apparatus for locating a valve stem aperture in a wheel. The invention includes a locating station having an overhead camera to scan the wheel. The scanned image of the wheel is received by a controller and is divided into radial zones. The controller locates the radial zone that defines the valve stem aperture from the scanned image of the wheel. The wheel then moves along an assembly line to a stemming station. A robot is positioned at the stemming station. The robot supports a valve stem insertion tool and a valve stem aperture locating sensor. When the wheel reaches the stemming station, the robot moves the valve stem insertion tool and the valve stem aperture locating sensor to the radial zone that defines the valve stem aperture. The robot moves the valve stem aperture locating sensor along the radial zone that defines the valve stem aperture and locates the valve stem aperture. The robot then moves the valve stem insertion tool into position and inserts a valve stem in the valve stem aperture.