I'm sure I read the range as 10 - 15 for a single axle. All my info is out in the trailer.
I've settled on 12 per cent as a target, but I'm not going to worry as long as I'm in the 10-15 range.
As in, I'm not going to stop and re-weigh the tongue after filling the fresh water, or after emptying the fresh by filling the black.
Escape Trailer Industries site specs are: 19' - approx. 256 hitch, 2510 trailer dry weight. 17' - approx. 250 hitch and 2100 trailer dry weight.
So, 12 per cent for either seems reasonable to me.
When I tried my new Sherline scale I found a hitch weight of 310 lbs. The trailer was hibernating so all the tanks are empty and there is nothing in the fridge, no beer under the bed.
I'll be weighing the hitch again after loading up for our first trip and probably redistributing and reducing weight. Until then, I'm working in a vacuum.