I think you'll find on the forum that we've only had, I believe, one report of a Sailun tire failure. Heartland has been putting them on the heavier fifth wheels since, generally, the 2015 model year (2014 builds, essentially). Not sure why you would be losing that much pressure in that short a time. We maintain our Sailuns at 110 psi (cold) and I probably have to put a few pounds in them maybe every three months or so (i.e. when they get down to 104-105 cold psi).
It's your money so you can replace them if you want. A good set of seven Goodyear G614's will run you around $2,500 mounted and balanced. If you go that route, might offer the takeoffs for sale on the forum as I'm sure someone would be interested in them.