If you check the unloaded height of the rear and compare to the laden height this will usually cause the camber to increase and perhaps the toe out as well.
This is not an issue with a solid rear axle
, but with the IRS it could be.
The suspension is designed to work within a range of ride height and if it is lower tire wear could be accelerated and also not handle as well.
The Airbags simply put the suspension in the proper area.
Again research indicates that the use of airbags to level the TV provides 1/2 of the benefit of having a weight
distribution hitch. Mostly by putting the rear end at the proper level. This provides more advantageous roll coupling front and rear and with the trailer. The leveling of the TV with the WD is a large part of the reason for it's use.
The other is the transfer of weight
off the rear to the front wheels and the trailer wheels. A lot of stress accompanies this weight shift as well. This is of course why many manufacturers discourage the use of WD hitches.
If you want 1/2 of the benefit of the WD hitch, and a level car so that the headlights are the same towing or not, keep the rear tires
from wearing, and improve the handling for about $100.00 then try it.
If it doesn't match your idea of the proper universe then (of course) don't add them. They do not add load capacity to the car, just add enough spring rate to bring the car back to level with the additional load.
The reason I brought it up is if you measure the ball height of the trailer hitch and set the ball on the car at that level then you merely add air to keep it there when loaded.
Lots of benefit and little cost.