Obviously boat trailer tires sit more than they roll!!
After 4-5 years they are history with me with only a few thousand miles on them.. Unless you use "E" range tires which just about last forever!
I learned my lesson years ago stuck on I-95 in Liberty City at 11:00pm
on a Friday night on my way to the keys with a flat tire....
It was not a fun time!!!
Your life is not worth a set of tires on a vehicle or a trailer..
Just my 2¢ worth.