Goodyear Marathon.........
This is an old post of mine, but it is just what you were talking about:
This is a good time to bring up a situation that happened to me this summer. While towing in Northern Ca this summer I had a huge bubble on the outside of one of my trailer tires. This was the second one on a two year old RV. I switched it out and kept going until I got to Chico Ca. The tires were all Goodyear Marathon radial "D" rated trailer tires. I found a Goodyear dealer in Chico and showed him the tire. His response was that he wanted them all.
The next day I took the trailer to his shop. He called Goodyear for authorization to change the set of tires. He was told that the Goodyear Marathon had in fact had a recall for tread seperation, but is was the "E" rated tire that had experienced tread seperation, not the "D" rated tire. That left me to ponder just replacing the one tire, or paying for all four. Fortunately the dealer was knowledgeable about these things, and called Goodyear back and got a different customer rep this time. He authorized the change of all of the tires on my trailer. I only paid labor and balancing.
The moral of the story here is that tread seperation is not normal for any tire that is manufactured correctly (and not overloaded). The tires were new, the trailer was new, and I was far from overloaded. If you have Goodyear Marathon Trailer Radials, take note!!!!
Contact a Goodyear dealer and inquire about the tires on your rig. I put the new model Series E tires on the trailer, and have not had a problem since. Be careful out there!!!!!!!!