Originally Posted by Guntr
I'm no expert, but I would think your safety chains only need to be just over your tongue weight. It's not like you are lifting your whole trailer off the ground with them like a trophy fish.
Probably more than the tongue weight, but not the full trailer weight either. Yes, if your TT pops off the hitch it will have to support a load approximately equal to the tongue weight. But if you are moving, it will also have the force required to move the 9,000 lb trailer. It doesn't take nearly 9,000 lb of force to move the trailer however. I would think doubling the tw would probably be sufficient, but I'd have to go back to college physics to be certain.
Oh yeah, and since there are two, each is only carrying half the force.
BTW. I used stainless steel quick links on my chains too after the spring clip on one of my hooks broke.
You could also look at a locking carabiner specifically used by climbers. They have pretty high working loads, and are intended to stop people from plummeting down mountain faces. But the higher working load ones may also be too big for your attachment points.
ETA: these are the 'biners we use for our camp hammock for quick release. http://www.mec.ca/product/5007-000/b...rewgate-biner/
Just checked the specs and they are rates at 25kN force or about 5600 lbs each (or over 10,000 lbs for a pair). C$10 ea (about US$7).