 In my Run Like a Dream book series, I explore lesser-known expert tricks for getting tip-top performance on your model railroad. One of the topics I'm exploring in book 2 of the series, Rolling Stock, is wheel sets having too much side-to-side slop in the trucks. One wheel set can get offset from the other wheel set, causing the truck to dog-leg down the track, angled as shown here, which leads to extremely derailment prone trucks. So how much side-to-side slop is just right? Let me provide some examples. You want just a slight amount of slop, about a half a flange width, so the wheels roll freely. The side-to-side slop in this truck is perfect. What about these trucks? Nope. Very sloppy. These need to be replaced. What about these trucks? I'd say they are okay, but borderline. If you see derailments, replace them with better trucks. What about rollability? Ideally, you want the wheels to spin for at least 10 seconds with a finger flick. That's it. These spin great. 13 seconds. How well do athern blue box trucks do on a spin test? Not great. Only 5 seconds. How well do the first trucks we tested with ideal minimal side-to-side slop spin? Let's find out. Yep, they're still spinning. They're slowing down. Wow, 22 seconds. This proves minimal side-to-side slop does not have to hinder rollability. This just scratches the surface of what I cover in the Run Like a Dream book series. See the MRH Store for more.