Steel wheel on the left, about 2" between the U-bolt and the weld for the bearing housing, wire wheel on the right, about 1". This also shows the effect of the different wheel offsets, and why the axles need to be different lengths as a result - most of the brake gear and the back-plate nuts and conceled in the well of the stud-mount wheel, whereas those with a wire wheel are clearly visible. Note this is a feature of the wheel offset, not the axle length, to see which axle you have you must measure the tube as described.