Does anybody else have an issue with longer rolling stock binding up on Kato Unitrack 12 3/8" radius curves? I seem to be having an issue with several pieces of my rolling stock that I can't figure out. A 50' Athern box car rolls fine, however a 50' Atlas box car and a 60' MicroTrains centerbeam flat car seem to be "sticking" and causing a lot of drag once they hit a 12 3/8" radius. As I am just starting into N Scale, I am not familiar with any of the ins and outs of how things work. I would think that a 12 3/8" radius would be plenty big for this size rolling stock. Would a truck replacement work? Or maybe go to metal wheel sets? Which leads me into another question with passenger cars..... Am I going to have the same binding issues with the modern passenger cars? Thanks for any help.