What the title says. I have no idea why it is doing it. I have the powered wheels setting set to true. I have antennas and batteries on both the tractor and the trailer, but even after powering off the antenna on my tractor truck, the trailer wheels continue to spin when I move the truck. I don't see why it should care about what the trailer does after I disconnect it. Powering off and powering on again my tractor breaks the connection, it seems, and restores behavior to normal. It would seem that this might be a bug in SE.