Do Airbags Count Toward a GVM Upgrade?

If you’re getting your 4WD ready for a long trip and the rear drops the moment you hook up the caravan, it’s usually the same question:

“If I fit airbags, does that count as a GVM upgrade?”

Fair question, because airbags do change how your vehicle sits and feels under load. But they solve a different problem to a certified GVM upgrade, and mixing the two up can leave people thinking they’re legal when they’re not.

Let’s break it down. In this guide, we’ll explain what airbags and upgraded springs actually do, how they differ from a certified GVM upgrade, and why levelling the vehicle isn’t the same as increasing your legal carrying capacity.

What airbags do

Airbag suspension (helper airbags fitted to the rear) is essentially a tuning tool for towing and changing loads. By adding air pressure, you can reduce rear squat when the caravan is hitched, level the vehicle, and improve the overall stance and stability feel. They’re especially handy if your setup changes week to week, because you can adjust them depending on whether you’re running empty during the week or loaded up for a trip on the weekend. They’re popular for exactly that reason, they’re adjustable and the results are usually immediate.

What springs do

Upgraded springs (including leaf packs where applicable) are designed to carry weight consistently, without relying on constant adjustment. Instead of “dialling in” pressure like airbags, springs provide a more stable base setup for how the vehicle carries load day to day, particularly when you’ve got a touring fitout that stays on the car. Depending on the setup, they can be constant-load springs for vehicles that are regularly heavy, or progressive/variable-rate springs that suit drivers whose loads change more often.

What a GVM upgrade actually is

A certified GVM upgrade is a legal capacity increase (where available) delivered through an engineered suspension package and the correct compliance pathway. If you’re heavy all the time and your towing load changes a lot, the best setup is often both, a compliant base (GVM upgrade) plus airbags to fine-tune levelling for different loads.

The myth: “If it sits level, I’m legal”

This is where the confusion happens. Airbags can make an overloaded vehicle look and feel better by levelling it up and improving the stance, but they don’t automatically change your legal carrying limits.

So do airbags count toward a GVM upgrade? Not on their own.

In some setups, airbags can be included as part of a broader suspension plan, but fitting airbags by themselves doesn’t mean your GVM has increased. Your legal GVM and axle limits stay exactly what they were unless the vehicle has been upgraded through an approved and certified process.

Many people think heavy-duty suspension or airbags mean they can carry more, but in reality it may just handle the load better while your legal weight limits stay the same without certification.

Handling More Weight vs Being Allowed to Carry More

The simplest way to understand it is that suspension upgrades can help a vehicle cope better under load by improving stance, control, and comfort, but they don’t automatically give you a higher legal GVM. Unless the upgrade is approved and certified, you can’t claim any increase in capacity, even if the vehicle feels more stable. So yes, a vehicle might physically carry more after suspension changes, but that doesn’t make it legal.

There’s also an important catch, even if the car sits level, you can still be over GVM, over a front or rear axle limit, or over your tyre load rating, and those are the issues that tend to show up when it matters most, hard braking, crosswinds, or rough roads. Levelling the stance doesn’t change the actual mass sitting on your axles, tyres, brakes, and chassis.

When airbags are a great solution

Airbags are genuinely useful when they’re used for what they’re designed to do.

Airbags make sense when:

You’re within your legal limits, but the rear squats when towing
Your load changes a lot (sometimes towing, sometimes empty)
You want adjustability for different towball masses or water tank changes
You want to fine-tune ride height and stance without committing to a constant-load spring package

Airbags work best when they’re set up and inflated sensibly. Using high pressures to “fix” a heavy setup can make the rear ride harshly and change the way the vehicle handles in ways most people don’t expect.

When Springs Make More Sense

If your vehicle has a constant touring fitout, springs and matched shocks are often the better base.

Upgraded springs and shocks make more sense when:

You run a fairly constant setup (canopy, drawers, fridge, tools) and tow regularly, so you want stable, consistent handling
You’re doing long distances, corrugations, or rough roads where shock control and heat management matter
You want the vehicle to carry the load properly without constantly adjusting air pressure

You can always add airbags later for fine-tuning ride height, but springs and shocks are often the better base setup.

When a Certified GVM Upgrade Is the Correct Fix (and what it involves)

If you’re regularly near the limit, especially once towball download is included, you’re likely looking at a certified GVM upgrade. A few common signs are needing high air pressure just to get the vehicle sitting level, the rear suspension spending a lot of time close to the bump stops or bottoming out, or the steering feeling light or vague when loaded. If you’re getting regular sway or instability, or you’re seeing unusual tyre wear, that’s also a sign the load and suspension balance needs a closer look. Keep in mind weights tend to creep up as accessories go on, so it’s worth rechecking your totals occasionally.

What’s typically involved in a certified GVM upgrade

What’s involved in a certified GVM upgrade depends on your vehicle and the approved kit available, but it usually includes an engineered suspension package, commonly upgraded springs with matched shocks or struts, plus supporting components as required, installed to the required standard and backed by the correct compliance pathway and documentation for that specific vehicle and kit.

Alongside the hardware and paperwork, the real-world checks matter just as much, including confirming actual weights (ideally axle weights and towball download), verifying tyre load ratings, and setting up alignment, geometry, and ride height properly. The key point is that a GVM upgrade is a complete system plus compliance, not just stronger parts.

For more info, read our Comprehensive Guide to GVM Upgrades in WA.

When You Might Need Both (GVM Upgrade and Airbags)

This is where doing both in one plan makes sense because you’re tackling two different needs. You want a solid, compliant base that carries the weight properly every day, and you also want the flexibility to fine-tune ride height and balance when your towing setup changes.

You might need both if:

Your 4WD is heavy all the time because your touring build stays on (canopy, drawers, fridge, tools, long-range tank, barwork, second battery), so you need a suspension package that’s designed to carry that constant load properly
Your towing load is variable, meaning you’re not always towing the same thing or with the same towball mass (different caravans or trailers, water tanks full vs empty, e-bikes on the rear, changing payload in the caravan), so your rear height and balance can change trip to trip
You want a setup that’s legal, stable, and adjustable without guessing, so you’re not relying on more air pressure to hide an overloaded setup, and you’re not constantly fighting rear squat, sway, or vague steering when the load shifts

A good way to think about it is that a certified GVM upgrade gives you the compliant base and the suspension control to carry your load properly, while airbags give you the levelling and fine-tuning you need when your towing setup or load changes from one trip to the next.

Choosing the Right Option: Airbags, Springs, GVM, or Both

Option	When it's usually the right move	You'll likely need this if...
Airbags	Levelling & adjustability	Rear squats when hitched, your load changes week to week, you want to fine-tune your ride height for different towball masses or trip setups.
Springs & Matched Shocks	Constant-load stability & Control	Touring fitout stays on, you tow often and for long distances, you want consistent handling without adjustment pressures.
Certified GVM Upgrade	Legal capacity increase & Engineered Base	You're close to or over your payload when loaded, towball download and accessories are stacking up, you don't want to rely on levelling to mask overload.

Key Takeaways

Airbags are great for levelling and fine-tuning your setup when your loads change, especially when you’re towing. Springs and matched shocks are better for carrying and controlling weight consistently day to day, particularly if your touring fitout stays on the vehicle. And if you need a genuine increase in carrying capacity, a certified GVM upgrade is what makes that increase legal and backed by an engineered system, rather than just stronger parts.

If you’re not sure where your setup sits, book a suspension check at DAPCO Bunbury so you’re working off facts, not feel. We’ll assess your load, towball download, and suspension, then recommend the most practical and compliant path for how you travel.

Airbags, Suspension & GVM FAQs

When are upgraded springs and shocks a better option than airbags?

Upgraded springs and matched shocks are usually the better option when your vehicle carries a constant load most of the time. They provide a stable base setup that supports weight consistently without you needing to adjust pressures all the time, and the matched shocks improve control over bumps, corrugations, braking and sway. If you tow regularly or do long hauls, springs and shocks typically deliver a more predictable, planted feel than relying on airbags alone for support.

What are the signs my setup is relying on airbags to mask an overloaded vehicle?

A big sign is needing high airbag pressure just to make the vehicle sit “normal” or keep it off the bump stops. Other signs include the rear still feeling unstable even when levelled, light or vague steering when loaded, persistent sway, frequent bottoming out, or unusual tyre wear. If the only way the vehicle feels acceptable is with more air, it’s often a hint the underlying issue is too much weight (or weight too far rearward) rather than a simple levelling issue.

What is towball download (TBM), and how does it affect my vehicle’s payload?

Towball download (TBM) is the downward force the caravan or trailer applies to your tow ball. That weight is carried by the tow vehicle, so it uses up your payload and loads up the rear axle. In practical terms, TBM is one of the most common reasons people unknowingly creep over their GVM limit, especially once you add passengers, fuel, accessories, and touring gear. Even if the caravan is within its own limits (ATM), TBM can still push the vehicle closer to (or over) GVM or rear axle limits.

What’s typically included in a certified GVM upgrade (where available), and what paperwork comes with it?

A certified GVM upgrade usually involves an engineered suspension package (commonly upgraded springs and matched shocks/struts, plus supporting components as required for that vehicle), installed to the required standard under an approved compliance pathway. Paperwork typically includes documentation confirming the upgraded GVM rating and compliance details relevant to the approved scheme used for that vehicle, along with any required identification or certification records that accompany the upgrade.

What’s the best first step if I’m unsure whether I need airbags, springs, or a GVM upgrade?

Start with a towing and load setup check or a weigh-in, so you’re working from real numbers, not feel. The key pieces are your actual vehicle load (ideally axle weights), towball download, tyre load ratings, and how the suspension is behaving under your real setup. Once you know whether you’re dealing with a levelling issue, a constant-load setup, or an actual compliance limit, the right solution becomes clearer. Sometimes it’s as simple as load redistribution or correct airbag setup, and sometimes it points to springs or a certified GVM path where relevant.