Looks like a steer tire that was pretty much wore out to begin with.
I've been in the opposite end of a tire shop when a fellow employee had a split rim blow off.... There was a parts room in the middle of the building between me and the part of the shop where it happened, but my ears still rang for quite a while after.
I think I hit my head on the bottom of the alignment rack when it blew off ...
And to think that I actually spent the afternoon after lunch today, mounting truck tires .... I have at least 4 more to do tomorrow morning 1st thing as soon as I get to work.