Tin plate track

Yes. What are you referring to by "regular 3-Rail track"?

K-line supersnap,atlas and tubular.

1) I have no knowledge of K-Line "supersnap".

2) Atlas O is solid nickel silver and has a more prototypical "T section" rail profile.

3) To be clear, even "Tin Plate" track is tubular. However there are other much more scale-like hollow rail configuration track systems, such as Ross Custom Switches, Gargraves, MTH "ScaleTrack", and Lionel "Fast Track", that tend to have a more prototypical rail profile.

I was wondering if I had to buy tinplate track if I wanted to run a Tinplate train.

Although I certainly have no experience with "Tinplate trains", I sure can't see why ANY Tinplate locomotive would not operate on any three rail O-Gauge track. Now if you ar talking about "Standard Gauge Trains", that would be a whole different situation.

Since there is an actual Tinplate Forum (sub-forum) here on the OGR Forum, you might ask your question on that forum.

Tinplate trains tend to have fairly large flanges on the wheels.  As a result, such tinplate may have some issues running on some of the more "realistic" three-rail track which does not have such high rails; the flanges will tend to bump along on the ties. But it is not a universal problem, just some tinplate and some track... so try to check for compatibility with the combinations you plan to use.

So would a Lionel or Mth train have a problem running on tinplate rails ?

Nope, a lot of folks do just that, so long as it is the same gauge.

thank you so much!!!!