How is railroad wheel diameter measured? Is it at the flange, the tread or somewhere else? Thanks!
I think it would be the actual tread where is contacts the rail.
IIRC, wheel diameter is measured at the flange side of the “flat” wheel tread, at the point where the flange fillet starts. This is also the point from which flange depth is measured.
Chuck (modeling Central Japan in September, 1964)
I am a member of the “great unwashed”; I don’t know how to measure track gauge and neither do I know how to get a (HO) transformer to run N-Scale locomotives and I am equally certain that I don’t have the slightest idea how to measure wheel diameter either so I’m going to pass on my knowledge of this subject.
Circumference of the tread divided by pi.
Generally, this is true - however sometimes the diameter is measured without the steel tire on there - ie. the diameter of the center casting. Also, the diameter of the tire can vary from the nominal figure by 2-3 inches - when a wheel lost its profile, or got flat spotted it would be put on a big lathe and turned back to true.
Wouldn’t it be easier just to measure the distance across the hub with some calipers?
Tom