I bought the popup in 2007 from the original owner who told me that he just changed all 3 tires 3 mos before i bought it (april 2007) and since then, i have put at least 4,000 miles on the trailer, and the only thing i have done as far as tires goes, is to park the trailer on wooden boards, (i have never covered the tires because they are not in direct sunlight) and keep the tires inflated to 65PSI no more, no less and i do not overload the trailer when towing. BUT with that being said, the tires still have alot of tread left on them but are starting to get cracking in the sidewalls and they have to be at least 7 years old so it is time. I have read all the problems with Carlisle tires, and im sure i have been lucky, but i tend to stay with what works for me, and like i said, this will be the last year with the popup since we will be upgrading hopefully
:B