Thomas, Percy, Toby, Mavis, Salty, and Diesel are recommended for 15" radius curves or higher. Like Anthony said, most of the 4-wheeled stock is capable of maneuvering 15" radius curves, and I'm pretty sure the bogie stock minus the express coaches can handle 15". Hope this helps
![Smiley :)](https://www.bachmanntrains.com/home-usa/board/Smileys/default/smiley.gif)