I was driving down the road and I saw in the side view mirror that one of the trailers tires looked wobbly. I pulled over and I had to remove that tire and put in the spare.
You can see the tire has deformed radially however the rim is still straight. I'm thinking some cords in the tire failed (??)

Moments away from a blow out.

That thing is crooked as a coons crank.

The treads separated. Common on trailer tires. It is the sitting around for long periods of time then highway speeds. They kind of dry rot and blow up before they actually wear out.

Sure glad you saw that before it let go.