I've been following this post for quite a while and just came back to it after we bought our Montana Mountaineer mid Sept. Of course it came with GY Marathons which I don't trust at all due to 2 of them coming apart on my tri-toon boat trailer. So after reading lots of rv forums and doing lots of research I bought 4 Sailun S637's from "Rustybore" on ebay.
$800 shipped to my door, now these are some SERIOUS tires. The Marathon weighed 37 lbs. the Sailun weighed 61 lbs, lots of steel belts and rubber. I could collapse the Marathon by just pushing down on it, couldn't even budge the Sailun. The sidewall is about an inch thick, I was very impressed. We have only taken 2 short trips so far but I'm very happy with them. So run what you like but don't rawdog a product that you don't use or haven't even seen.