i found this as i was looking for a black knobby wheel 9c without hoses cast (found one btw)...i found a 45 tread model with hoses cast...not listed on nicks guide...could this be a new variation or just one freak model that had fine tread wheels applied to it...here are some pics
the model you can see the fine tread wheels
hoses cast and the fine tread in this pic
the rivet looks legit to me
another angle of the fine tread and hoses cast to be seen
the model has glue on the wheels as i would guess it was on a train layout or a diarama