3 or 4 inches seems a tad on the low side, but then again I remember somebody giving an example of a US tilting train being barely faster than a conventional Eu

3 or 4 inches seems a tad on the low side, but then again I remember somebody giving an example of a US tilting train being barely faster than a conventional European train on a similar curve due to more conservative standards prevailing across the pond. In Germany, up to ~5" (130 mm) are permissible on the main line network. In theory and exceptionally, even values up to 6" (150 mm) are possible, although haven't really been used in practice so far as far as I know. The maximum speed for trams/streetcars/light rail is often based on a maximum deficiency of 150 mm, too. Tilting trains in Germany can use up to ~12" (300 mm) of cant deficiency, but then again in Germany they really seem a dead end so far.