Prototype wheel sizes

Model Railroader General Discussion (Model Railroader)
1

The questions I have involve freight car wheel sizes on contemporary North American railroads, here in Australia. We typically use 36#8221; wheels on most freight trucks, as I am in the process of replacing all the plastic wheels with metal ones and I would like to make them prototypically correct.
I have read in previous issues of MR that, as a general rule of thumb, that the prototype uses;
a. 33#8221; wheels in 70-ton trucks.
b. 36#8221; wheels in 100-ton trucks.
c. 38#8221; wheels in 125-ton trucks.

  1. Does this mean a truck with 33#8221; wheels can carry a maximum weight of 70 tons?

  2. Would a fully loaded 50#8217; boxcar that weights around 110 tons use 33#8221; wheels?

  3. What size wheels would be used on the following?
    a. 5-unit Gunderson Maxi-3.
    b. Thrall 5-unit Articulated Double Stack Car.
    c. 5-unit All Purpose Spine Car.
    d. 86#8217; Auto parts boxcar.
    e. 86#8217; TOFC

2

70/100/125 tons are “nominal”, and don’t exactly correlate with reality.

The 86’ cars are generally 70 ton, but not all of them…

On the five unit cars; look at the drawings that have appeared over the years in MR and other mags. This is way out of my era, but there is at least one type of 5 unit well car with 70 ton trucks (33" wheels) at the end, and 125 ton trucks (38" wheels) at the four middle positions.

3

Also, I believe some 86’ tri-level auto racks run 28" diameter wheels. This may be due to there excessive height. A lot of the centerflows run 36", but I’ve seen them with 33", so you may want to do some research on a particular car or type.