Jack Delano captured this view of Mr. Edward E. Leonard pushing a driver wheelset in place under an engine being wheeled. We’re at the Shopton locomotive shops of the Santa Fe railroad in Fort Madison, Iowa in March of 1943.

A locomotive’s drivers experience wear, and are built such that the outer ring (the tire) is removable for re-conditioning or replacement. We’ve seen this earlier photograph of a tire being replaced on it’s wheel.