Well, I dunno about the OEM tire being "total crap".
Mine are (iirc) duro tires on my 2011 831RLBSS.
They survived a trip from elkhart Indiana to Comox British Columbia, after which I subjected them to this trip:
Not one peep, squeak or complaint.
They're two years old now and look fine. Yes, I know what to "look" for in a tire to know if it's "good". Condition, appearance, wear, life cycle (age), etc. It's part of what I do for a living and I'm very good at my job.
But I'm also very fastidious with tire pressure, never overload the GTWR and hang around 100 kph ( approx 62-ish mph). I get passed by guys doing 75mph or better pulling huge trailers with newer diesels all the time. I just shake my head, chuckle to myself and watch 'em disappear over the horizon knowing full well those trailer tires are well above thier rated speed....
Now, does the OEM put the lowest price unit they can on thier trailers?
I have no doubt they do. They're out to make a profit after all. But if the tire is rated for the weight, they're not really doing anything wrong. OEM car manufacturers do the same thing.
I've often wondered if OEM tires on trailers are doomed from the get go from the method of delivery. Ie: the independent trailer hauler guys.
I can't count how often I've seen these guys on under inflated tires, well above the speed limit and/or trailer so out of balance to get it on thier particular tow vehicle it's not funny. They also are typically very long hauls in these conditions to reach all four corners of the continent.
Time is money for these dudes, stopping to frig with tire pressures or going the tires rated speed cuts into thier bottom line. They'll do it until they don't get away with it (ie: blowout) and it starts costing them money.
Thousands of miles in an overheated condition will take years and thousands of miles of life off the tires before you even get them.
I'd say the real reason these tires die an early death is, like everything else in life, a multitude of reasons. Abuse, overloading, under inflation, overspeed, road hazards, min spec to begin with, etc.
I'm not saying the Chinese tires are the greatest, but maybe early failures are not always a design/manufacturing fault....