The suspension nerd in me appreciates all the questions! Long post, but those who know me know I cannot resist suspension topics. That aside, I hope the response helps.
Absolutely positively on this truck (26 Sierra 3500 DRW), with this rig (2025 340RL) air bags are
not a necessity. However, they will improve safety, ride quality under load, reduce the likelihood of overcorrection in some emergency maneuvers, and compliment my hitch setup.
@George Sagging too much does not automatically mean you're over GVWR or GAWR. Sag is just spring rate versus load at that point in the travel a truck can squat a little or a lot and still be comfortably under every rating, and you can be
over a rating without dramatic sag. Adding airbags does not raise GAWR. That number is set by the weakest link on the axle line.
Capacity is not my reason, nor will airbags ever address a lack of capacity. Like
@2 Allies said, every truck squats some under the loads we put on them and taking that squat out is my deliberate goal. With rear squat, weight comes off the front axle, which does most of the braking and 100% of the steering. Leveling puts some of that weight back on the steer axle (this is the biggest gain especially if you are truly concerned about safety), settles the rear, and keeps the trailer sitting level (bags do not act in the same way a weight distribution hitch does...less weight is transferred back to the front). This product replaces the overload springs and introduces a progressive compression rate. The question on that is “so what?” Again safety and ride comfort. Body roll will not be as dramatic and reduces the likelihood of the driver over correcting when it matters most (deer, downtown Atlanta). This is where I am taking a gamble…a rolling sleeve air bag should help match the frequency of the front suspension (if my research is right…hobbyist not an engineer). That is what will really improve ride feel, reduce porpoising, decrease fatigue, reduce wear and tear on the trailer, etc.
Separate topic, but I’ll also be adding an upgraded sway bar at least in the rear. Not that I can say Hellwig bars are the best, but I’ve used them before and they really perform. SRW or DRW, I can absolutely promise every owner reading this that if you upgrade at least the rear sway bar (meaningfully) you will have tremendous gains in stability loaded and unloaded. Fact check me on this, don’t take my word. The difference in controlling lateral movement by upgrading a sway bar is objectively measurable and you will notice it in all driving conditions. For a few hundred bucks and no more than 20 minutes under the truck, it could be the most meaningful upgrade you ever make to your truck…cars too for that matter. Keep in mind you can add too much stiffness with a sway bar...which is one of the reasons I like Hellwig as they are adjustable.
@Lantley You are spot on on both of your points. The Hensley Air Ride is doing real work, but it's working a different axis than airbags. The air hitch decouples and dampens the fore-aft chucking between truck and trailer; air springs level and stabilizes the truck's own rear platform. Complementary, not redundant. So, the Hensley manages the dynamic forces at the connection point where the bags mange the geometry, roll, and vertical behavior of the truck under the load.
Anyhow, it's the right thing for me and part of my hobbyist pursuits of working on vehicles and especially their suspension. Again...I'm just a hobbyist but i never look for confirmation bias. I'm pretty sure the above is reliable and unbiased.
