Jeff,
Sorry to hear about your tire problems. I've had the "pleasure" of changing one on the side of I-95 just outside of Washington DC, on a very hot August afternoon. Regardless of where it happens, changing a trailer tire on the side of the road is not one of those things that you want to do too often.
Like everything, you can find good reviews and bad reviews for anything on the internet. I can say that I have had good experience with Goodyear Marathon tires on my boat trailers over the past 10 years. My first and only Goodyear Marathon tire failure was last summer on I-95. I attributed the failure to UV damage from the sun since the tire that blew was my spare tire. It had been mounted, unprotected on the trailer and in the sun for 4 years. Other than 2 nail punctures, I have had NO problems with Goodyear Marathons and have towed 18,000+ miles.
The "dimples" that you refer to......a slight indentation in the tire sidewall that goes from the tire bead towards the tread in a straight line.......is pretty normal with radial tires and is cosmetic in nature.
Goodyear, like most companies have moved their manufacturing facilities to China. Has this impacted quality? Who knows. There are other variables which will also affect tire performance. Air pressure is one, and the tires should be inflated to the max pressure indicated on the sidewall. Towing speed is another, as most trailer tires are rated for a maximum speed of 65MPH. Tire load range (B, C, D) vs weight being towed is another.
On the web, you will find some like bias ply tires and swear by them, some like radials and stand by them as well. Some say Carlisle tires have reliability problems, but others love them. For me, I'll stick with the Goodyear Marathons.
Phil Belcher
2003 266CCR
496 MAG, Bravo 3