*EDIT* this is a used 5er that we will be purchasing from owner, that has had it sitting on jacks on a concrete slab of a campground for over a year or so!!!! I know, the great Tire(d) debate/re...
My last 5th wheel, a Keystone Everest, was very similar in weight to yours. I put on Michelin LTX truck tires LT235/85R16 and toured the country for two years without any tire issues. I'm running Michelin XPS Rib on my current trailer. You'll never see me with any tire stamped Made in China on any of my trailers as I don't like blow outs. If you insist on ST's may I recommend the Maxxis M8008, which aren't made in China.