One time I picked up a loaded trailer in Houston, did my usual pretrip, and took off for Louisiana in the dark. The long bridge was closed because of an accident, so we all got off onto the detour on Highway 190. At a stoplight somewhere northwest of Baton Rouge, this Cajun guy in a pickup pulled up on the shoulder next to me all excited, said my brakes were out on the trailer, he saw sparks. It was worse than that. The hub was broken, three studs were broken clean off, and three or four of the others had rounded holes in the rim of the outside wheel big enough to slide over the lug nuts, and most of the rest of the lug nuts were loose. I wasn't far from losing the dual, and would've if there hadn't been a detour and that guy hadn't stopped me.
You guessed it, whoever had that trailer before me had a flat and someone got too happy with an impact wrench. Some things are hard to find with a pretrip.