I have airbags on my truck and here's why.
When towing with just my trailer on the back I put little
air in them.
I can easily tighten my chains enough to make the rear
axle light. In fact last time out I tried to go up one more link
in my chains hoping to cut down on the rocky horse bounce.
First stop sign was a right turn and my tires squeeled as I
attempted to pull away from the intersection
(My fresh water tank is in the front end of my trailer
and it was empty.)
Pulled into a parking lot and went back to the normal
link on the WD hitch chains.
On occasion I haul a motorcycle in the back of my truck
and sometimes I even add fire wood in addition to the
cycle. On those occasions I put 75 PSI in the air bags
and we ride nice and level.
AND on the RARE occasion when I go to the land fill
and purchase a heaping load of mulch, the air bags are
great as I can ride away with level bed while many
others look like they're about to drag their rear bumper
on the way out
(It's real hard to "go up a link on the chains" when
you don't have a trailer on the back!!)