I'm on my 4th set of tires for my 22 year old 5th wheel.
All sets have pretty much stayed flat across the tread. No rounding or scuffing. In fact the tires will stand up on their own when I take them off of the trailer for bearing maintenance or other work.
I do make sure the pressure is correct before and during each trip.
The one time I had a tire with a rounded look to the tread the bands had separated inside of the tire. It was very noticeable and was causing that tire to rub against the front tire on bumps in the road. I began seeing little puffs of smoke in my mirror.