Update on Nitrogen filled tires.
After 4 1/2 years and about 6000 miles I did notice that I had to add air much less frequently than with air filled tires. I have heard many times that once a tire is 5 years old no matter what they look like, replace them. My Sunlines Mission Tires went at 5 years and were bias Ply. At the beginning of this season I had a complete check up after 4 years on my 5th wheel. I asked about the tires being radial and Nitrogen filled if they would last longer and they said probably another two years.
In July on a two lane road in the Adirondacks a tire completely fell apart and destroyed a $200 fender trim along with it.
My conclusion: Bias or radial, air filled or Nitrogen filled, replace them at 5 years old.
I checked all the ratings on every trailer tire known to man and there is no tire with a good rating. Only those that are not as bad as others. I settled for Goodyear Marathon class D and one of them went flat the next trip a week later. It wasn't seated properly but caused me to change a tire again in the campsite this time. Or I should say AAA changed it for me. No problems since then and I do notice a much smoother ride with them if that's possible.
Paul & Sheri - Upstate New York - SUN-0258
Amateur Radio KD2KCY - VHF 146.520 MHz
2012 F150 F/X 4, 6cyl EcoBoost, Max Tow pkg
2013 Rockwood 8280WS 5th wheel
2006 Sunline Solaris T-1950