been told that on new trailers the bearings are not as good for whatever reason
The boat and trailer I sold last year was still on its original bearings after 10 years of occasional trailing the length of the country and launching into saltwater inumerable times per year. Good waterproof grease/bearing buddies/ and once or twice a year strip down
had them under one of our smaller boats. Never felt safe with them as I couldnt get in there and strip/grease them. Would never have another.
Wouldnt bet all a surprised to hear a bit of a rumble from an unloaded jacked up wheel, --strip, clean and grease probably sort it.
Now brakes thats another matter--mild steel and salt water