I have to agree with BigSkyJimmy, the current Goodyear Marathons are not the problem. The problem is putting them on an already heavy trailer that many overload and then insist on traveling over the speed rating of the tire.
I believe it was Fauch that mentioned in another thread the speed factor on any tire and in particular ST tires rated for 65 mph. Overload it, heat it up on a hot day and then drive at 70 - 75 mph and you can expect problems.
Keep in mind also, China did not build a tire and then come to the US looking for a brand to put on it. Goodyear went offshore to have these tires made to save money as do other US tire manufacturers.
As Wiley75 says, there are some very good tires made offshore, I have used Toyo and Hankooks and would not hesitate to put them on any of my vehicles. I just don't want LT tires on my heavy Monty and would only look at a G rated tire to replace my Marathons.
I am completely amazed that no one seems to ever blow any other brand of tire, perhaps because this is a Montana forum, but let me tell you I see them every day of the summer and they are not all Marathons nor are they all Chinese made.