Violent tire blow out messed up my rig

I have a 1993 30ft class a fleetwood coronado on a p30 chassis. Im super on top of maintenance and safety but on the way back from my last trip a rear inner tire blew out and mangled the under storage cabinets. It literally blew the doors clean off. I managed to get them back in place and limped home on 1 tire. all 6 tires were replaced about 7 months ago and only have maybe 2000 miles on them with nice even wear. They are samson 8r19.5. Definitely a cheaper tire. After closely inpecting these tires i noticed that every single one of them has small stress cracks on the sidewalls. Why are these tires failing already? Should i replace the blown out tire with another cheap samson? Id really like a new set of goodyears all around after this experience but these tires are so fresh still! Minus the stress cracks. I was running 90psi all around. The sidewall calls for 110psi which seemed high to me. What tires do you guys run? Are crazy blowouts like this common?