Jimmc wrote:
Snip... Beyond that, the weight on the jack starts getting bigger and you have more leeway to attach the chains. The question is whether or not that "just touching" point or something just slightly beyond it gives enough slack to attach the chains without too large a load on the jack.
That is the proper way to use the jack to relieve the pressure from the chains for hooking up. You should have a jack that is strong enough to lift the back of the truck as high as needed to easily lift the bars into place or hook up the chains. The higher you lift and make the truck/coupler into and inverted V or a tent shape the easier it is.
Most use a 3000lb or 3500lb jack which should do the job easily. Mine is an Atwood 3500lb model and my tongue weight is just short of 1300lbs.
Barney