ONAIR / Product Guides
What size air tank do you need?
Gallons, PSI, refill time and trunk space - explained without promising a made-up number of air-ups.
Choose tank volume for the reserve you need and the space you can safely use, then match the compressor to refill it. A larger tank at the same pressure stores more air; it does not automatically create higher pressure, faster movement or less total compressor work.
Describe the tank's internal volume.
Describes pressure, not how large the tank is.
Depends on compressor output and the pressure range being refilled.
01 / THE DETAILS
The tank is your reserve, not your compressor.
The compressor fills the tank. Management releases stored air to the suspension when you request an adjustment. The compressor then replenishes the air that has been used.
That reserve helps the system respond without waiting for the compressor to supply every adjustment directly. Once tank pressure falls, performance depends on the air remaining, the required suspension pressure and the flow path.
02 / THE DETAILS
Separate volume from pressure.
Gallons measure the tank's internal volume. PSI measures pressure. Two different-size tanks can share the same maximum working-pressure rating and still hold different amounts of air.
At equal pressure and temperature, a larger tank stores more compressed air. That does not mean you should raise the pressure to compensate for choosing a smaller tank.
The maximum rating is a limit, not a recommended compressor shut-off setting or a suspension driving pressure. The tank, compressor, manifold, plumbing and safety components must all be suitable for the operating range.
03 / THE DETAILS
Compare sizes by the trade-off.
| Size class | Why consider it? | What to check |
|---|---|---|
| Compact, roughly 1-2 gallons | Tight packaging or a discreet installation. | Less reserve; normal adjustments may trigger filling more often. |
| Around 3 gallons | A middle-ground starting point for space and reserve. | The actual car's air demand and the chosen compressor's recovery. |
| Around 4-5 gallons | More reserve when space and use justify it. | More mounting space and more air required to refill the same pressure range. |
The best tank is not necessarily the biggest. Measure the installation first and compare the current available options. A custom hidden setup and a visible trunk display can have very different priorities.
04 / THE DETAILS
Why there is no fixed number of air-ups.
How much air a lift uses depends on suspension volume, vehicle load, starting height and target height. Available reserve also depends on tank pressure and whether the compressor is running during the adjustment.
Line size, valve flow and fittings influence how quickly air moves. A larger tank alone will not remove a restrictive fitting or make every car lift faster. Likewise, a smaller tank can fill sooner from empty with the same compressor, but supplies less reserve.
A larger tank may change how frequently the compressor cycles, while individual refill periods become longer. Check duty limits and fill performance, not just start-up frequency.
05 / THE DETAILS
Ports and mounting can decide the layout.
Plan connections for compressor supply, manifold feed, pressure sensing or switching, drainage and the specified safety devices. Count usable ports after allowing for brackets, trim and access.
Thread labels matter. G-thread and NPT fittings are not interchangeable just because the nominal size looks similar. Use the tank's exact thread specification and compatible sealing method; never force a mismatched fitting.
- Measure the tank with fittings installed, not just the bare cylinder.
- Keep the designated drain reachable.
- Allow space for mounts, protected lines and service tools.
- Use the correct plugs and safety components for the system.
06 / THE DETAILS
Choose reserve and recovery together.
Compare a compressor's output and duty limits at the pressure you intend to use. Dual compressors can add recovery capacity, but also need the appropriate power supply, protection and plumbing.
Use the tank-and-compressor matching guide to plan those choices together. Do not assume a tank of a particular size always requires one or two compressors.
07 / THE DETAILS
Leave room to maintain it.
Drain collected moisture using the correct procedure and inspect the mounting and connections. A water trap does not eliminate condensation inside the tank. The finish may be part of your trunk design, but accessible servicing is part of a functional installation.
Never exceed the permitted working pressure, alter a pressure vessel or loosen a fitting under pressure. Follow the installed equipment's instructions for drainage, pressure control and safety devices.
ONE MORE THING
The questions that come next.
Does a 200 PSI-rated tank mean I should run it at 200 PSI?
No. A maximum rating is a limit. The operating range must suit every component and the manufacturer's control settings.
Will a bigger tank solve slow air-up?
Only if inadequate reserve is the relevant limitation. Valves, lines, fittings, pressure and suspension air demand also influence response.
Can I choose the tank by gallons alone?
No. Dimensions, port locations, threads, mounting, pressure rating and service access are just as important.
Is an aluminium tank maintenance-free?
No. It still needs moisture management and inspection. Material and finish do not remove the servicing requirements.
Sources & equipment references
General education is not a replacement for the instructions supplied with your exact components. Product-specific ratings and procedures do not transfer automatically to another setup.
- Current ONAIR air tanks
Actual capacity, dimensions, ports and ratings vary by product.
- VIAIR technical FAQ
Model-specific compressor and tank limits; do not transfer ratings between brands or models.
- Air Lift Performance: tank moisture
Why stored compressed air requires a drainage routine.
