My workshop neighbour is a trucker and he told me this story that happened to him, while he was running East-West across Australia, way back in the late 70's or early 80's.
He only had one truck, but he got white line fever, running Perth to Sydney and return, and he drove about 20hrs a day - 7 days a week!
He was much younger and super-keen back then, and he loved the money rolling in! - to the point, at one stage, one dispatcher asked him, "how many trucks he had?".
When he replied "only the one", the dispatcher wouldn't believe him!
Of course, traffic was much lighter back in those days, driving hours had no limitations, and it was a bit of a free-for-all on the roads - as evidenced by the number of crashed trucks, back then.
Anyway - he told us he was hauling this triaxle trailer behind his KW, and he was well West of Adelaide, on the Eyre Hwy, nearing the Nullarbor Plain, in the middle of the night.
Nature called, and as the truckies were prone to do back in the good old days, he pulled up, unzipped, and let fly from the cabin door. Once done, you'd zip up, back in the cabin, and "on the road again!", as Willie says.
So, he's stopped on the shoulder having a whizz, after coming down a long gradual grade, onto a flat - when to his utter amazement, a set of duals trundled right past him, travelling steadily up the centre of the highway, at about 50kmh!!
Stunned, he jumped down and walked back to the triaxle trailer, only to find the centre set of RHS duals completely missing!
He told me he figured that the hub and duals must have gradually walked out, and must have come right off, only a minute or so before he pulled up.
He reckoned they must have travelled steadily down the grade behind him, and then went past him, right as he stopped to take a leak.
He said the worst part was, he had no way to re-install the duals - so he chained up the offending axle, and got going again.
But then, he said the trailer handling at speed, became something like a wild animal! - it was all over the highway, and he couldn't get it to pull straight!
So he stopped and pulled the wheels off the other end of the axle, just leaving the front and rear axles intact.
He chained up that side of the axle, and he said after he did that, the handling became a lot more controllable.
I guess he wasn't loaded to the limit, or the remaining tyres would've been seriously overloaded.
He made it O.K., in this axle-less manner, to a civilised town on the Western end of the Nullarbor Plain, where he was able to organise to have the unserviceable hub repaired.
He was in awe of the fact that this set of duals and hub had travelled right up the white line neatly for possibly 3 to 4 kms, and no-one had come the other way and collected them, in that period of time!