I think the 1985lb is the derated value of the 2185. Your supposed to derate the load rating by 10% if you use a P rated tire on a high profile vehicle like an SUV or RV. I don't know how you classify an Airstream since it has a low center of gravity. You get 1986lb if you devide 2185 by 1.1. If it is already rated for LT use then 2185 is a good number.
You won't have any problems with any tire rated 108T or an XL rating. My trailer tops out at 7000lbs and I am having no issues.