1. HUB FACE (1)--Prepare the axle: Remove the wheels and tires from the axle to expose the hub faces. (2)--Locate the hub face: The hub face is the flat surface on the hub where the wheel sits flush against it. (3)--Use a straight edge: Place a straight edge against the hub face on one side of the axle. (4)--Measure across the axle: Place the end of your tape measure against the straight edge and extend it across the axle to the corresponding hub face on the other side. (5)--Read the measurement: The measurement on your tape measure is the hub face measurement.
