Trailer Tires

I bought a new elcosed & the factory tires came apart the second season of using it.
We never leave the shop until the air pressure is correct.
I replaced them with a set of cheap trailer tires from a vendor of mine.
They are branded (gladiator) 225-75-15.
Paid 400 for all 4, mounted & balanced.

They are a 10ply trailer only tire.
Now have two sesons on them & they look great, no wheather cracks at all.

I also have a set of these on my open trailer, same results.