Herb,
One thing that I found up on the cars on the loop is that some of the wheels actually were painted. There was a white stripe about 6" wide painted from one side of the wheel to the other, looking like a stripe through the axle. This stripe was so the engineer could look back and the conductor could look ahead to see if all of the wheels were turning and one was not sliding in the consist.
The only reason that I remember these is because I was asked to repaint them on the edges of the wheels for the same reasons up on the Loop.
Rick Steele