Track radius in O scale?

[Goldnut]

63D and 72D. Is the center rail the radius of the track? I laid out 2 arcs of 31 1/2 and 36R. Set the track over the marks and they dont seem to line up right on the ends. I can post pics later today. Thanks Ken

 

[Iron Horseman]

EDIT - I stand corrected..... Learn something new every day.

Depends on the brand, Atlas is measured from center rail. O-63 and O-72 O-gauge tracks should be 31.5" and 36" radius respectively. However I have to say I have never actually measured them. Lionel (and I assume the other high rail tinplate) appears to be measured from outside tie.

Here is the track I use.
http://i2.wp.com/freemodelrailroadplans.com/news/wp-content/uploads/2013/05/Curves_Atlas_21st.jpg

Here is Lionel
https://3.bp.blogspot.com/-qOuZJAkXNrA/VsOY_xWkK6I/AAAAAAABOxE/qpx8MGnXER8/s1600/lionel002.jpg

 

[Brakeman Hal]

In O Scale 2-Rail which I use, the actual Radius is stated, not the Diameter as with Lionel O Gauge.
Brakeman Hal

 

[Goldnut]

This is Gargraves track. Guess I should have included that in my first post. I see on their website that 63"D track is actually 63.89 center to center and the 72 is73.42 C to C. If all else fails...read directions!

 

[Sirfoldalot]

This is Gargraves track. Guess I should have included that in my first post. I see on their website that 63"D track is actually 63.89 center to center and the 72 is73.42 C to C. If all else fails...read directions!

Typical man -- LOL