Im not a 100% positive but I think the wheel spacing (width) is different. 13.8 vs 14 mm is coming to mind but again I am not certain.

If using C Track, you will likely have no problem using the original DC wheelsets. The only thing is that the DC wheels are insulated on one side, meaning that they will not provide ground contact to both rails for lighting or contact purposes. My solution to this has been to reinstall one axle in the opposite sense, so that one axle per bogie conducts to each rail. When installing an axle contact, this will result in contact with both rails. WARNING, coaches and cars modified in this manner can no longer be used on 2 Rail DC layouts without restoring the original setup.

If using AC wheelsets, they are designed differently, in terms of spacing, in terms of isolation and in terms of shape of the flanges and coning, to help both operation on Marklin track (originally M Track) and ground return.

For a pilot coach, I would recommend installing the AC wheelsets, because the coach will be used at the head of a consist being pushed and remaining on the tracks at switches is more important than it would be for a trailing coach. If the pilot coach is equipped with Roco's wheelset mounted direction switch, this will have to be reinstalled on the AC wheelset. I think that the two newest IC2000 models have a digital decoder for direction change (lighting).

Regards

Mike C

The DC based 2 rail wheel sets use slightly different specifications in spacing and the 3 conductor Maerklin wheelsets have taller flanges than the DC wheels.
Also if you use S88 detection, then having wheels that are electrically connected is important to get those cars to register occupancy.

The larger flanges, at least on C-track turnouts, allow the wagon to roll through the turnouts without dipping down at the break in the track, while smaller wheelsets will temporarily dip and thus not roll smoothly.



This could cause other running issues, but usually doesn't make a difference.