Hard to tell what caused something like that. I replaced 235/85R16 BFG Commercial TAs on the fiver with Michelin XPS Ribs summer before last. They were 8 years old with over 90k on them and zero failures.
As an example of unknown causes, I threw a retread on a rear truck tire a year and a half ago. I was planning on replacing them at the end of that trip and just wrote it off to age and wear. The three weeks later I was lubricating the TrailerSaver hitch and found a 3" long 1/2" bolt with a washer welded on it in the hitch frame. Obvious wear from bouncing around on the pavement and nothing off my equipment - most likely the culprit in the tire failure!