Maybe. Maybe not. For instance, Bachmann 0-6-0 says it needs 18 but I bet I could run 15's

 

15" radius



flyerrich;

The 15"radius curves were intended for trolleys, or other short wheelbase equipment. You can try your engines and see what makes it and what doesn't. I recommend taking out the 15" and installing wider curves, if you can.

Traction Fan

 

The RR I'm modeling is the Los Angeles Junction Ry that has a place w/ HO equivalent 10" R. Put down a 1/4 circle of it & ran Athearn CF7 & Atlas S-2 + 40' car around it in both direction w/ no problems.

 

My little 0-6-0 Mantua Camelback easily negotiates 6" radius curves because the middle drivers are blind...

 

Back when we built our first layout space was an issue and we tried 15's, The Athearn SD 40's and longer rolling stock would jump the track or bind in the curve on the 15's. Most shorter locos and stock did OK
Now 3 builds later there's 22's and up with only 3 18's in the whole layout.
IMHO more realistic and smoother traversing of curves.

 

Check your coupler clearance and truck travel, most times it is that not being able to move far enough that causes problems. Ladders and suchlike can get in the way. My DD40 AX has been 'chopped' and can take 15"s! Steamers are more snicky, they mostly will not take anything under 24" but you never know, my BLI 2-10-2 takes 15's no problem right out of the box, the Bachman 4-8-4 is another story, it won't do anything less than 24"! Rolling stock is a crap shoot, some will go anywhere and others will ONLY go on WIDE turns. Kinda a pain but each individual type of loco and roller have different needs for smooth rolling operations. Some "tweaking" of each piece of stock is sometimes needed.

 

I run 4 axle GP locomotives on 15" radius curves with no issues.

 

The only way to know for sure is to test it. Make sure you test groups of cars coupled together, as it's often the car bodies or trucks that don't have enough clearance.

 

I have found that Athearn Blue Box 4 axle diesels and 40ft rolling stock from that era will normally work if not run to fast. Anything bigger has issues. I have also found that most newer locomotives have more issues with the tighter curves than the older ones did.

I have an 18r turn and a 17r turn heading into my turntable. Not a big issue since the table can only handle locos 9 inches or less. All other curves are 22 or greater on mine.