It does sound like you may have run over something.
Saying that, I have noticed most that have posted here that have run very old tires or Chinese tires without issue all have relatively light trailers. I can assure everyone that it is a completely different ball game with a larger, heavier trailer and the China bomb issue is very real. I had a Carlisle tire fail on me last year while bringing our new to us fifth wheel home last year. I was lucky that I felt a vibration and managed to get stopped before any damage occurred. The tire had a HUGE separation on the edge of the tread. I now run Sailun S637 Load Range G tires which are the only Chinese tire that I would recommend at this point in time because they are constructed to a higher standard than the standard Chinese ST tire.