Power King Towmax STR's came as OE on our TT.
They lost between 2 and 4 pounds of pressure during 5 months of storage.
I think that's good. Does it matter? I don't know.
We have about 2,000 miles on them.
One thing that I have noticed about them is that they have a very strong odor of oily/paraffin? after getting warmed up. From what I've read it is the preservatives and oils getting moved around in the tire and coming to the surface. I think that it is a good thing. I had a pair of Kendas on a popup and they also had an odor when warmed up but not near as strong.
Trailer tires are meant to be used not stored.
"All TOWMAX STR tires are required by TBC to exceed the Federal testing minimum by 40% on average"
From this page;
Towmax - about-us
Sounds like a very impressive product to me.