The dry weight of the Elite II is about 1300 lbs more than the Escape 21. That could explain some of it. I asked Dennis about that on our visit to Chilliwack earlier this month. As I recall that was part of his response as well. That said I have always used Michelins on my vehicles for the last 30 years and have never had a bad one. Costco uses nitrogen too.
Since 78% of the atmosphere is N I don't worry too much when I have to air my trailer tires from my shop compressor.
ST and LT sidewalls are stiffer and provide less flex than P tires. I have not found any distinction between ST and LT other than ST should only be mounted on trailers not driven vehicles. What have you found to be the pros & cons?
Here's a link that seems to be lacking hype:
Trailer Towing – ST Tires vs. LT Tires | RV 101® your education source for RV information