I've added Intermountain semi-scale wheels to a couple of cars, and see no issue with them on my Fast Tracks turnouts.
On the other hand, I'm surprised how little difference they seem to make, appearance-wise. I expected to see a big improvement, but honestly can't see that much difference from the fatter wheels. I just got new glasses yesterday, though, so I'll go back and look again! ).
I'm going to run them for awhile before I decide whether or not to convert everything over.
Mark P.
Website: http://www.thecbandqinwyoming.comVideos: https://www.youtube.com/user/mabrunton
Some very good info throughout this discussion. Thanks to all who contributed.
May I suggest an old trick for those with "fat" steam drivers? Most of the electrical contact on such drivers comes at the flange, so one way to disguise a "fat" wheel is to paint the outside half of the tire black. One way to do this is to paint the entire tire, then run the model upside down with clip-on leads and clean off the paint to the inside with a Q-tip moistened with acetone. WARNING: The acetone won't care what paint it eats, so be VERY careful not to get it on painted surfaces you want to keep painted! Also, acetone definitely will eat styrene plastic, so keep it away from that too!
If this trick does not allow for acceptable electrical contact, wheel to rail, you also can add a phosphor-bronze contact shoe made from, e.g., the Atlas custom switch contacts. The tips of the "T" are bent upward so they don't catch on switchwork or guard rails. But, I find that Floquil paints work fine here.