Get rid of them ASAP.
We had a very similar thing happen, but we lost two of them within miles of one another on Father's Day this past year leaving us stranded at a gas station until we could have them replaced with GY 614's by roadside service (no Sailuns available). Our first blow out was on the highway doing about 65mph. I was being chased by my other half in our Mini Roadster and the force of the blowout caused the trailer to jump up in the air about 2 feet per witness accounts. I practically didn't feel it in the truck, but heard and knew immediately what had happened and got off the shoulder immediately. It took out our fender, bent the metal wrap, severed the electric brake wires, the tread hit the top of the jack and broke it's fitting causing most of our hydraulic fluid to leak out, and tore up a lot of the underpinning. The tread wrapped itself around the axle about 4 times and was very difficult to remove. The tires on that side of the trailer were suffering from an alignment wear issue already, it's still a mystery today as to whether the tire failed due to excessive wear, heat or just being garbage in general. I knew it wasn't air pressure since I had just checked them before we left the house about 4-5 hours prior.
The second tire I fortunately caught just before it actually blew when we went up a mile to the next exit to check the air in the spare, etc off-highway. That's when I discovered that the second tire had a separation in progress. The tires on this side were not showing signs of mis-alignment wear. It's hard to see in the picture, but I knew what I was looking at with the second tire immediately having been in the retail automotive and tire industry for a good portion of my career. Our Bighorn was only 8 months old when all of this happened and maybe had 4000 miles on it. I was trying to get a year out of them and already had planned to have them changed out, but we didn't make it.
First two images are of some of the damage. Last image is of the tire that was separated while still on the 5th wheel at the place we stopped to check them.
Good luck with it and don't let it dampen your trip!