@bob2 posted:A Mogul with rigid drivers would probably do 36" radius, but the problem is always the lead truck and drawbar.
That has been my experience - mainly the lead truck.
Realism and tight radius are opposites.
That is inaccurate as a general statement. How tight a radius can you run an 0-4-0? Or, single truck trolleys vs. 2 trucks trolleys? Or, B-B vs. C-C diesels? Wheel arrangement is an active variable.