Actually the road wheels are partially correct. What it is supposed to represent is the wear of the road wheel touching the tracks, but they made it to deep. All you would have to do to shave the wheels down, so the wear marks are not too deep.This would be shown on new road wheels that have had heavy useage only.
The Mouse House ones, that are worn do not show the wear marks and would have to be added to the road wheels to show this.
This is shown on the road wheel on the right: