I have some older AMS rolling stock (Tank on flat) that behaves badly on my RR. I have checked the wheel gauge and it is OK. I believe the problem is semi-scale flanges and very little transition curve from the tread to the flange. I have replaced some with Aristo wheels, but this requires drilling out the bushing on the AMS truck and shortening the axle on the Aristo wheels. Before I do this irreversible mod to more cars, I thought I would look into drop in replacements.
I am not looking for finescale or even semi scale. I want wheels that will track well on less than perfect track. Bachman Spectrum (F Scale) and most recent AMS wheels do fine.
Before you suggest it; I know I could try getting wheels from AMS, but even their new wheels have less flange than I would like.