Originally Posted by ruscal
One thing I did learn though was that when torqued to yield the tube sides were concave, and when returned to zero rotation the sides were flat. That means the corners of the tube would eventually crack at some future cycle number.
How does all this explain Thane's trailer cracks? I have no clue, but something attacked that poor tube.
Maybe you found the smoking gun. That coupled with compromised structure from road debris sandblasting and rust might be the answer. Great effort at solving the puzzle.