tire blow outs

I just had a rear blow out, inner dually. The bang! scared the beejeebies out of me, but there was no change in handling. I've watched the Michelin video many times and pray that I can be levelheaded enough to remember to step on the gas when a front tire blows in order not to lose control. I wish there was a place where you could practice that skill. The tire that blew was one that had repeated air loss, and despite having it looked at time and time again it would lose air when it sat. I always checked pressures and made sure it was properly inflated prior to any trip. It was checked that morning before departing and had the appropriate pressure in it. Bad tire? Bad valve stem? Just had the valve stem replaced on that tire about 2 weeks prior to the trip. So who knows.

Tires were 7 yrs old but placed into service on my RV 4 years ago.