I didn't have a blowout while pulling the 5er, but I did have the right rear blow out at highway speed while pulling one of my heavy equipment trailers, and I had a pretty good load in the truck box as well. I had checked the tire pressures less than 100 miles earlier, and all was OK. It was a load range E 235-85-16 tire. The failure event was not as scary as many people imagine. There was a loud "pop", a lot of vibration, but no serious loss of control. I do believe when such an event occurs that it is best to slow down easy while heading toward the road shoulder. Heavy braking may lead to loss of control, but I haven't tried that. If slowing down easy and in a fairly straight line means damage to the rim or wheel, well so be it. In my case the rim was not messed up, but on that particular day I was not carrying a spare tire as I was too concerned about carrying way too much weight. So I had to call my son to bring out a spare wheel and tire. He was about 1.5 hours away. I have had only 2 massive tire failures in my 50 years of driving, that it is statistically almost never.
Paul_in_MN