Airbags
The Suspension Aid, Not the GVM Solution
The Suspension Aid, Not the GVM Solution
Rear suspension airbags (often called "helper bags") are one of the most popular 4WD accessories on the market, especially for those towing campers or caravans. They promise to level out your ride and stop the dreaded "rear end sag."
However, airbags are also the most misunderstood modification in the 4WD world. If used incorrectly, they can lead to chassis damage and give you a false sense of security regarding your legal weight limits. Before you install them, run your numbers through our GVM Calculator to see if you are solving the wrong problem.
Airbags are fantastic at one specific job: leveling a load. If you hook up a heavy caravan, the rear of your vehicle drops and the nose lifts. This reduces steering control and braking efficiency. Inflating airbags raises the rear back to a neutral position, restoring proper geometry.
But here is the catch: Leveling the vehicle does not change the weight on the axles. It just masks it. A vehicle sitting perfectly level can still be dangerously (and illegally) over its GVM or Rear Axle Capacity. Do not use airbags to hide the fact that you are overweight.
This is the most critical rule of touring. Installing airbags does not increase your GVM by a single kilogram.
If your vehicle has a payload limit of 600kg, and you load 800kg into it, pumping up the airbags might lift the suspension off the bump stops, but your chassis, brakes, and axles are still overloaded. If you are consistently hitting your weight limits, check our calculator to see if you actually need a dedicated GVM upgrade (suspension and certification) rather than just helper bags.
On most 4WDs, the airbags are installed inside the coil springs or beside the leaf springs, often replacing the factory bump stops. The bump stop is a critical component designed to absorb the final impact when your suspension fully compresses.
When you remove the factory bump stop to install an airbag, the airbag becomes the bump stop. The problem arises when you over-inflate the bags to carry a heavy load.
Unlike factory suspension, airbags require active maintenance. You cannot simply install them and forget them. A cardinal rule of airbags is that they must never be run completely empty (0 PSI).
If an airbag has zero pressure, it can get pinched between the coils or suspension components as the vehicle moves, tearing the rubber bag. Most manufacturers recommend keeping a minimum of 5-10 PSI in the bags at all times, even when the vehicle is unladen, to maintain their shape and prevent damage.
Airbags are an excellent tool for variable loads—such as a ute that carries tools during the week (heavy) and runs empty on weekends (light), or for occasional towing. They offer adjustability that static springs cannot.
However, they should be the final piece of the puzzle, not the first.