Interesting & helpful thread. My open trailer's had Michelins on it forever, 14" to keep the trailer low, definitely not trailer tires but originally for small RVs. Been through several states and never a look-see from any authority.
They've been bulletproof, even carrying 4500 lbs.
I've been very lucky, as even though the trailer leads a very pampered life (heated garage, never out unless working), the tires are (gulp) from the late '90s. Two years ago I took it to NorCal & back on a banzai run.
I've cheated disaster long enough, so even though the tires still look mint, it's not going anywhere until it gets new rubber.