How to Adjust Airbag Suspension Pressure (2026 Guide)
Airbag suspension only works properly when the pressure matches the load you're carrying. Too low and you lose the support you fitted the kit for. Too high and the ride turns harsh and uneven. Here's how to check and adjust it properly in 2026, whether you're running a manual gauge or a digital controller.
- Check airbag pressure unladen first, then again fully loaded, before you decide how to adjust airbag suspension pressure.
- Most load assist kits run low psi unladen and higher psi under load — never exceed the maximum psi stamped on the airbag.
- A digital controller such as the Boss Auto Pressure Controller Kit with PX06 Compressor lets you adjust pressure from the cab without crawling under the vehicle. Buy for daily towing use.
- Uneven side-to-side pressure is the most common adjustment mistake — recheck both airbags after every change.
- Log your unladen and laden settings once you've dialled them in so you're not guessing next trip.
Why this matters
Airbag suspension only does its job when the pressure suits the load on the back of the vehicle. Rear-end sag, a bouncy ride when empty, or the vehicle sitting low with a caravan on the tow ball usually comes down to the wrong pressure, not a faulty kit.
Most load assist airbag kits are designed to work with your vehicle's existing suspension, not replace it. The airbags add support that you adjust with air pressure to suit whatever you're carrying that day. Get the pressure wrong and you either lose the benefit of the kit or end up with a ride that's too firm for unladen driving.
This guide covers how to check pressure, how to adjust it safely, and what to do when something isn't behaving the way it should.
What you'll need
- A tyre pressure gauge rated for the psi range of your airbag kit, or the digital controller supplied with your setup
- An air source — a 12V compressor, workshop compressor, or service station air hose
- A notepad or phone to record your unladen and laden pressure settings
- Your vehicle loaded the way it will be for towing or carrying, so you can test under real conditions
- The fitment or installation instructions that came with your Boss Air Suspension load assist kit, which will list the maximum psi for your specific airbags
If your setup runs a digital controller, such as the Boss Auto Pressure Controller Kit with PX06 Compressor, most of the manual gauge work below is done from the touchscreen in the cab instead.
The steps
1. Confirm your kit's pressure range
Check the fitment sheet or instructions that came with your airbag kit before touching anything. Every load assist kit has a maximum psi stamped on the airbag itself, and running above that figure risks damaging the bellows.
Most load assist airbags are designed to run low psi unladen and progressively more as load increases, but the exact figures vary by kit and vehicle. Skipping this step is the most common reason people over-inflate.
2. Set a baseline with the vehicle unladen
Park on level ground with the vehicle empty of any extra load. Check pressure in both airbags with your gauge or controller.
Unladen pressure should be low enough that the airbags aren't doing the work the standard suspension already handles. If the vehicle feels harsh over small bumps with nothing in the back, unladen pressure is usually too high.
3. Load the vehicle the way you actually use it
Put in the load you're planning to carry — camper trailer on the tow ball, tools in the tray, or the caravan hooked up. Testing with an empty vehicle only tells you half the story.
Check ride height at the rear guards against the unladen measurement. If the rear has sagged noticeably, that's your cue to add pressure.
4. Adjust pressure in small increments
Add air in small steps rather than filling to maximum straight away. Recheck ride height and pressure after each adjustment.
The goal is to bring the rear back close to level, not to lift the vehicle higher than standard ride height. Overinflating to compensate for a heavier load is a common mistake that leads to a harsh, bouncing ride and uneven tyre wear.
5. Match pressure side to side
Check both airbags again once you're happy with ride height. A difference of more than a few psi between sides usually points to an uneven load, not a fault with the kit.
If the load is genuinely centred and one side still won't hold the same pressure as the other, that's a sign of a leak, which is covered in troubleshooting below.
6. Test on the road before locking in the setting
Take the vehicle for a short drive, loaded, over the kind of road surface you'll actually be towing on. Pay attention to how the rear settles at speed and over bumps.
A setting that feels right stationary in the driveway doesn't always feel right at 100 km/h with a van behind you. Adjust again if the ride feels too firm or the rear still sags under braking.
7. Record your settings
Write down the unladen and laden psi that worked, ideally for each combination of load you regularly carry — empty, tools only, fully loaded and towing.
This turns future pressure checks into a two-minute job instead of trial and error every trip. If you're running a digital controller like the Boss Auto Pressure Controller Kit with PX06 Compressor, most models let you save preset levels so you're not guessing at all.
Troubleshooting
Pressure drops overnight or over a few days. A small drop is normal due to temperature changes, but a consistent loss points to a leak at a fitting, air line or valve. Spray a soapy water solution over joints and listen and look for bubbles.
One airbag won't hold the same pressure as the other. Check the load is actually centred first. If it is, inspect that side's fittings and air line for damage or a loose connection before assuming the airbag itself is faulty.
Ride feels harsh even at low pressure. This usually means the airbags are doing more work than they should for an unladen vehicle. Drop pressure further, in small steps, and reassess.
Compressor won't build pressure or cycles constantly. Check for a leak downstream first, then check the compressor's own fittings and the pressure switch setting. A Pressure Switch 110-135psi set too low will cut the compressor out before the tank reaches working pressure.
Gauge reading doesn't match a digital controller's display. Analogue gauges can drift slightly over time. Cross-check with a second gauge before assuming your controller is wrong.
Rear still sags under load at maximum recommended pressure. This is a sign the kit's pressure range has been maxed out and the load is heavier than the airbags are designed to support at that setting. Don't exceed the maximum psi stamped on the airbag to compensate — check whether a different kit or additional support is more suitable for that load.
Tools and resources
- A gauge rated for your kit's psi range, or an in-cab digital controller
- A reliable 12V or workshop air source
- The fitment sheet for your specific load assist kit, such as the Load Assist Kit for Toyota Hilux 4WD 2015+ up to 2-inch lift
- An Airbag Fitting Kit if you need to replace a worn valve or line while you're checking pressure
- A written record of unladen and laden pressure settings for the loads you carry most often
What to do next
If you're still deciding which load assist kit suits your vehicle and towing setup before you get to the pressure-checking stage, read how to choose the right load assist airbag kit for guidance on matching a kit to your GVM, lift height and typical load.
FAQ
What's the right psi for airbag suspension?
There's no single figure that applies to every kit — the correct psi depends on the airbag model, your vehicle and how much you're carrying. Always check the fitment instructions supplied with your load assist kit for the maximum psi and adjust from there based on load.
How often should I check airbag suspension pressure?
Check pressure before every towing trip or heavy load, and at least monthly if the vehicle sits unladen most of the time. A quick check takes a couple of minutes with a gauge or digital controller and avoids running under or over pressure.
Is it bad to run airbags at maximum pressure all the time?
Running at maximum pressure with no load causes a harsh, bouncy ride and unnecessary strain on fittings. Pressure should be adjusted down when the vehicle isn't loaded, not left at maximum year-round.
Can I adjust airbag pressure without a compressor?
You can use a service station air hose in a pinch, but a dedicated 12V compressor or an in-cab controller is far more practical for regular adjustments, especially when towing. Most owners fit a compressor alongside their load assist kit for this reason.
Why is one airbag holding less pressure than the other?
An uneven load is the most common cause, so check that first. If the load is centred and the difference persists, check fittings and air lines on that side for a leak before assuming the airbag has failed.
Does a digital controller make pressure adjustment easier?
Yes. A digital controller lets you check and adjust pressure from the driver's seat instead of crawling under the vehicle with a gauge, which matters most when you're adjusting for a load change on the road.
Do all load assist kits use the same maximum pressure?
No. Maximum psi varies by airbag model and kit, so always check the instructions for your specific kit rather than relying on a figure from another vehicle or another brand's product.
Will adjusting airbag pressure increase my vehicle's payload or towing capacity?
No. Load assist airbags improve ride height, stability and support at your vehicle's existing legal payload and towing capacity — they don't increase the manufacturer's rated limits unless paired with an approved GVM upgrade.
One last thing
The most overlooked step isn't the adjustment itself, it's writing the numbers down. Owners who log their unladen and laden pressure settings for each regular load stop guessing every trip and catch a slow leak early, because they notice the pressure isn't matching last month's log instead of assuming it's normal drift.
