Radius

[docaab]

Would someone know to what radius (in inches) the Number 5 and 6 turnout correspond?

[ABC]

None, number 5 and number 6 turnouts do not correspond to any radius. It is gauged by how many inches it goes in each direction (ie 5" in length for every 1" it goes across, so a #6 would be more gradual than a #5 which is more gradual than a #4.)

[jward]

just to expand on the precious post, using atlas as an example only because i know their geometry better than ez track:
#4, which is actually a #4.5, is 12.5 degreesangle at the frog
#6, 10 degrees angle at the frog.

that said, i've found that though they aren't a drop in replacement, #4 or #5 look and work well with 18" radius, #6 with 22" radius and larger. in fact, i would highly recommend the use of #4 or 5 switches instead of the 18" radius ones. they don't take up that much more room, and their operational benefits far outweigh any inconvenience this may cause.