From what I can tell in the picture, I agree it looks like tread separation. You're lucky most of the time, the first indication of a problem is when it blows out.
I would have the tire dismounted and get the advice of an in person tire professional as to whether you should look for axle problems. I'd also replace all of the tires as a set. After 3 years without incident, we had two tires blow out within a couple of hundred miles of each other. After the first blow out, we were going to replace the whole set when we got home. We couldn't find replacements in stock at our destination so we replaced the one and made plans for ordering replacements when we got back. Finally made it home on the spare. "Repairs" to the trailer cost as much as the tire and I did the repairs myself.
After a lot of research we decided to go with the Goodyear Endurance and went up a load rating from D to E. Newer versions of our trailer were shipping with E's. I want to say it was just under $700 for 4 tires total including 9% tax, disposal fees, etc... Unfortunately, we haven't traveled a lot since replacing the tires. When I replaced the set, I bought a spare rim off Amazon and had the new Chinese tire I had to buy mounted on it. Now I carry two spares, just in case...
Current RV Information: 2018 Forrest River Salem Hemisphere 282RK
Previous RVs: 2004 Fleetwood Bounder 32W; 1999 Four Winds Five Thousand 21RB; 1986 Allegro Bay 27'