Lets put this in perspective. Seven year old pop up without brakes and 2000 miles on it. It's not like a boat trailer that wants to suck water in when you back the warm axle into cold water. Yes, it's easy to clean and repack the bearings BUT most people do not know how to re-grease the bearings and many tighten them too much or too little. Without a pressure system for re-greasing it's hard to get grease ever where instead of just on the outside as most do.
Guess those that question using a small amount of 90 gear oil have never heard of oil bath wheel bearings where that's all that's used. Sorry, what was I thinking... this is the folding trailer section, not Class A.
OP, if the tires are original, they need to be replaced and I'd go with a bigger size, even buying new larger diameter rims if there's room for a bigger diameter tire... fewer turns/mile.
