The standard minimum radius curve for AZL locomotives and rolling stock is 195mm (7 11/16″).
There are some exceptions:
The AZL Brass Challenger steam locomotive will operate on 195mm radius curves, but for best operating results, we strongly suggest a minimum of 220mm radius.
The AZL Brass Big Boy steam locomotive will operate on 220mm radius curves, but for best operating results, we strongly suggest a minimum of 245mm radius.
The AZL RDC locomotives will operate on a minimum of 160mm radius curves, but for best operating results, we strongly suggest a minimum of 195mm radius.
Read more on the AZL Forum:
http://azlforum.com/thread/1031/minimum-radius-azl-locomotives-cars#ixzz53eZWIPLQ
http://azlforum.com/thread/1031/minimum-radius-azl-locomotives-cars#ixzz53eZWIPLQ