More trailer tire/wheel issues

I pulled my Cobra up the Sierras to Sparks, Nv and then blew the right tire (6� of tread separated and took the fender off too). Tire and wheel were Not even warm. Put on the spare and drove the final 20 miles. Next morning I jacked up one wheel and took 2 tires and rims in and got 6 ply trailer tires. After the contest, I pulled the trailer back down the western slope of the Sierras and pulled over to check things after about an hour of down hill towing. To my surprised both Hubs were too hot to keep my hand on them and the right hub was hot enough to steam as I poured a bottle of water on the inside wheel area. In downhill towing the surge brake stays on most of the time and is riding the trailer brakes............something we know to never do, right?
Are these two Instances related? I think so, I did the same trip last year and I’m thinking the overheating from downhill towing caused over pressure and weakened the 4 ply auto tires. The weakened tire blew after about 4 hours of driving on my way back up the hill, this year.
Your thoughts and experiences?
JJ