Actually both are wrong. (Well, at least for Germany. Poland might have some slightly different regulations for wheel sizes. So take this with a grain of salt.)
The Ty2 runs on standard track gauge, so the inner distance between rails equals 1435 mm.
59 mm * 25 = 1475mm, which is bigger than 1435 mm and thus couldn't possibly work.
In order to avoid the wheels running up the rail (which can cause the train to derail) the outer distance between wheel flanges (wheel gauge) must be slightly smaller than the track gauge. In Germany the wheel gauge must be inbetween 1410 and 1426 mm, so roughly 1-2.5 cm shorter than the track gauge. In 1:25 scale this would be at least 1410 mm / 25 = 56.4 mm and 1426 mm / 25 = 57 mm at most. Therefore ~57 mm would be the correct track gauge and the kit is wrong.
But i actually think that i know where Adrian Wandtke went wrong:
There is another measurement were the spacing of the rim backs (not sure about this translation) is measured . If you aren't paying attention or don't know the difference between the two, this could easily be confused with the wheel gauge. And wouldn't you know it: This distance equals 1360 mm, which divided by 25 is exactly 54.4 mm.
However all of that being said: You should stick with the 54.4 mm wheel gauge, that way the locomotive and tender match. A difference of 2.5 mm (1/10 of an inch) is also barely noticeable in this scale and i highly doubt anyone will be able to spot this, unless they are actively measuring your model.
Johannes
54~55mm (I would say… 54.5mm)
