Carter,is it my imagination or are the wheels and tires undersized on those buses?
Johnathan,
As Peter mentioned, the wheels and tires are on the small size. However, CMW uses the same wheels for their medium duty trucks (IH R-190, Ford F-600, etc.) as they do for the buses.
And if the prototype bus had 8.25 X 20 tires, the overall size may not be all that far off. The 20 inch truck rims that were so common in the 1950s are now
(almost) a thing of the past. But even today you can get tires for the now common 22.5 inch truck rims that range from approximately 36 inches in diameter up to at least 42 inches in diameter.
Carter
Edit: I found a place that is still offering 7.50 X 20 truck tires. They have an overall diameter of 36.8 inches. So it looks like the CMW wheels are still about 2 scale inches undersized for what would have likely been the smallest tire used on medium duty vehicles in the 1950s.
Another edit: I found some 7.00 X 20 truck tires that are 35.6 inches in diameter. That is getting closer to the 34.7 inches Peter measured for the CMW wheels.