My present set has only been on for about a year, no issues of course. The other set was on a different trailer and they lasted 6 years. I sold the trailer so I don't know if they're still in use. The previous trailer was a triple axle and I ran the pressure at 90 psi, but only running about 2,500 lbs/tire. The present trailer has around 3,500 lbs./tire so I'm running them 105-110 psi.
Since there is no movement, I don't see how they could "wear down" the bead section. I'd need some clarification on that from that "tire guy", but I've never heard of any such issue with them.