Just a few weeks ago I was camping and noticed that one of my 4 yr old Maxxis tires had an area that was swollen. I immediately ordered a new Maxxis from discount tire and replaced it, keeping the bad tire.
When I returned home I contacted the Maxxis warranty dept. and was assured that they would honor their warranty for the full 5yrs, and to take it to my local dealer where I purchased it. To make a long story short, they honored the warranty and gave me a brand new tire for $39.46. Mind you, this was not covered by a road hazard purchase like available through discount tire, it was covered by the Maxxis 5yr defect warranty. I was so thrilled I went ahead and purchased 2 more to give me a complete new set. I kept the three takeoff tires to use on my utility trailer and/or for spares.
I don't know of any other trailer tire that has a 5yr warranty against defects.