I am going to say the problem you described is unusual at the very least, and that would be true for any tire…
What needs to be known is why the tire(s) failed… and especially why multiple tires would fail within a very short time… that would be true of any type or brand of tire… when multiple tires fail at or near the same time I would suspect some event as a possible cause, but the tires should be analyzed especially tires that have been properly maintained used and still failed…
What did Maxxis say about the failures and what were the results of the warranty claims on them… surely you have demanded some answers and shouldn’t be shy about sharing those answers… if you haven’t you certainly should now… not only from Maxxis either, hopefully you filed a complaint NHTSA requesting a safety investigation….
I have done a fair amount of research concentrating on the M8008 radial and primarily in 15 inch for my 10,000 pound trailer… all of my research leads me to believe that Maxxis makes not only the best ST tire for my trailer but IMHO make the best ST tire… I want to know why your tires failed as bad as you do and am always in search of factual information to include the good the bad, and the ugly…
Of course the normal weight information is important as is the speed use a legitimate question on a speed rated tire…
It might be really helpful if you have some pictures of the tires damage…