I bought a couple of TRIX deep well articulated cars, thinking they were Marklin.
I have many cars that have DC wheels, and I have had very few derailment problems (those I have changed).
Should I try to get the correct AC wheels for these TRIX cars?

Hi
Exactly like Dave says, recent Märklin and Trix are exactly the same production, wheel spacing (must be 14.0 mm), flanges, etc.
C 6track and Trix track are almost identical except for two-rail electrical arrangements (frog connections and one additional switch in turnouts)

I converted a Trix 25241 (SNCF 241A65) into a Märklin equivalent and can say:
- same production
- insulated axles
- specific PCBs and slightly different decoders (program slight change)

On the other hand, I deal sometimes with temperature-related things that may cause derailments by cold weather (coupling cinematic to lubricate with dry silicon spray)

Cheers
Jean