Thanks, Mike!
Paul
Modeling HO with a transition era UP bent
I found this, a review from Jan., 2012 MRR.
http://mrr.trains.com/news-reviews/staff-reviews/2011/11/athearn-trains-ho-scale-u50-diesel-locomotive
Says at the bottom 18", only because the two inboard trucks drive, the two outboard trucks are free wheeling.
Mike.
My You Tube
I don't see the min radius mentioned here and have not found it in a google search:
http://www.athearn.com/Products/Default.aspx?ProdID=ATHG41007