Been a while since I played SE, and never really had this problem before. But lately it seems my large ground vehicles are having an issue with their wheels randomly (sometimes on world load, sometimes in the middle of play) suddenly merge with the ground, rendering the vehicle unable to move till it completely bugs out and destroys itself. Seems most common near ore deposits, but not exclusive to them. Also seems to be more common on wheels on a sub-grid (such as an attached trailer). I've used this vehicle before without these issues. Only way it seems to fix the vehicle is to copy and re-paste it in, though sometimes that doesn't work, as the vehicle will just hang in the air like a station, even though unsupported stations are turned off.