Everyone buys the tyre deflator and forgets the other half of the job. Letting air out takes a few minutes and a $60 gadget. Putting 20psi back into each of four tyres at the top of a beach ramp takes a compressor, a decent battery and, depending on what you bought, three minutes to a quarter of an hour.
The box won't tell you which. Most compressors advertise free flow, the airflow with nothing connected. That's not the number that matters when a 265/70R17 is already sitting at 30psi and pushing back. We compared five in-production inflators on the figures that do matter, and on price.
Which portable tyre inflator should you buy?
For anyone airing down most weekends, the ARB Brushless Twin Portable (CKBLTP12) is the pick, with the best published flow under load of any portable here. If your 4WD is a keeper, the hard-mounted Ironman 4×4 MX195 gets you most of that speed for about half the price. Everything else involves a trade.
- Best overall: ARB Brushless Twin Portable CKBLTP12, $1,575
- Best hard-mounted: Ironman 4×4 MX195 On-Board (IAC012), $799
- Best for smaller 4WDs and SUVs: Bushranger Max Air III (55X23), $425
- Cheapest twin-piston: Kings Thumper Max Digital, $299
- Best cordless, for top-ups only: Milwaukee M18 Inflator (M18BI0), $279 tool only
Why the free-flow figure on the box misleads
A compressor slows as pressure builds behind it. On the two units here that publish both figures, flow at 29 to 30psi lands at 67 to 76 per cent of free flow. Treat any free-flow number as a ceiling, and be wary when a brand won't publish what happens under load.
Manufacturer figures from ARB fitting instructions, Ironman 4×4 and Kings product data, Bushranger via ARB, and Milwaukee (1.41 SCFM at 0psi, converted). Ironman's body copy also quotes 130 L/min at 40psi. Prices checked 13 October 2026.
That's the trap with the Kings Thumper Max Digital. Its 300 L/min free-flow figure is bigger than the ARB's 260, yet Kings publishes no flow at pressure and no duty cycle. Both draw about 90 amps, and on roughly equal power it's unlikely the $299 pump moves more air at 30psi than the ARB.
ARB Brushless Twin Portable: the fastest air-up you can carry
The ARB CKBLTP12 is the one to buy if you air down often and run big tyres. ARB's fitting instructions quote 176 L/min at 29psi from twin brushless motors, the strongest at-pressure figure of any portable here, with 260 L/min free flow. It sells for $1,575 at ARB stores.
The details are well thought through. On a weak supply it shuts down one motor rather than flattening your battery, the clamps correct for reversed polarity, and there's a built-in air tank with a 7m hose. ARB backs it with a three-year warranty.
The downsides are weight, bulk and current. It weighs 13.3kg and wants 90 amps, so the engine runs while it works. ARB's website says 100 per cent duty cycle, but its spec sheet says 90 per cent at 22°C. Trail4Runner's 2025 test of the on-board version also found the brushless unit ran hotter and louder than the old brushed twin.
Ironman 4×4 MX195: best hard-mounted compressor
The Ironman 4×4 MX195 (IAC012) is the best value way to make airing up permanent. At $799 it lists 130 L/min at 30psi and 195 L/min free, with a 100 per cent duty cycle and IP67 dust and water sealing. Ironman claims it takes an average 33-inch tyre from 15 to 38psi in under two minutes.
Hard-mounting under the bonnet or in a drawer means no clamps, no lugging a case out from under the camping gear and a fused, permanent power supply. ARB's brushless twin on-board (CKBLTA12) flows more, at 176 L/min at 29psi, but costs $1,066 before you buy its pump-up kit.
The weakness is paperwork. Ironman's spec table quotes 130 L/min at 30psi, but its body copy says 40psi, so treat the figure with some care. We found no independent test of it. It also needs a proper install, so budget for fitting if you're not handy with 12V wiring.
Bushranger Max Air III: right-sized for SUVs and lighter 4WDs
The Bushranger Max Air III (55X23) suits drivers with stock-size tyres who want a tough, compact single-cylinder unit. It sells for $425 at ARB, draws a manageable 30 amps and weighs 5.3kg. Unsealed 4X4 found it took under a minute per tyre from 18 to 32psi on a Mercedes X-Class.
Its 72 L/min free-flow rating is modest, and Bushranger doesn't publish flow at pressure. The duty cycle is 33 per cent at 100psi, so on big tyres expect to pause. The 9m coiled hose reaches a trailer, though Unsealed 4X4's reviewer wasn't a fan of coiled hoses.
Kings Thumper Max Digital: cheap, clever and short on data
The Kings Thumper Max Digital is the cheapest twin-piston unit here at $299, and its best feature is genuinely useful. Set the target pressure, walk away and it switches itself off. Kings claims 18 to 38psi “in just over a minute”. It launched in July 2025 with a 7.75m hose.
The catch is what Kings doesn't print: no duty cycle and no flow at pressure, only the 300 L/min free-flow figure. It draws 90 amps through alligator clips, and Unsealed 4X4's first impressions rated the hose and fittings as standard quality. For the money it's a sound occasional-use buy, but don't treat the 300 as a promise.
Milwaukee M18 Inflator: a top-up tool, not a beach compressor
The Milwaukee M18 Inflator (M18BI0) is the best cordless option, but only for top-ups. It costs $279 tool only at Repco, shuts off at a preset pressure and runs on any M18 battery. Milwaukee claims it tops off a 33-inch truck tyre in under a minute.
Top off is the key phrase. Milwaukee quotes 1.41 SCFM at 0psi, about 40 L/min, and a 33 per cent duty cycle at 80psi. In Pro Tool Reviews' test, it added 6psi to a Ford F-150 tyre in 52 seconds. Scale that to 20psi and four 4WD tyres take around 12 minutes, plus battery swaps.
How long does it really take to air up four tyres?
On our numbers, between two minutes and a quarter of an hour of pumping, depending on the compressor. A 265/70R17 all-terrain holds roughly 75 litres of air, so going from 18 to 38psi needs about 100 litres of free air per tyre. Four tyres need around 400 litres, and flow at pressure decides the rest.
Our estimates, not tests. We assume about 75 litres of air in a 265/70R17 tyre (a geometric estimate), so four tyres need roughly 408 litres of free air to go from 18 to 38psi. Navy bars use the maker's flow at pressure; grey bars rest on a maker claim or a test on different tyres; the Milwaukee bar is scaled from a US top-up test on a Ford F-150.
The common claim is that cordless inflators can't do four 4WD tyres without stopping to cool. For the Milwaukee, at least, heat isn't the wall: Milwaukee's US launch material says its internal fan lets it run for over 20 minutes. The real limits are time and battery capacity. Cheaper cordless units with half its flow are worse again.
Getting back up to road pressure safely
RACQ suggests 15 to 18psi for general sand driving and 12 to 15psi for soft sand, then reinflating to your vehicle's placard pressures before you drive on the road. Queensland Parks warns that flatter tyres can roll off their rims if you go too fast or swerve, so air up as soon as you're back on firm ground.
Run the engine while the compressor works, connect straight to the battery terminals, and check pressures with a separate gauge once the tyres cool. Pack the inflator with your recovery tracks rather than under everything else, and if you're still choosing rubber, our all-terrain tyre guide covers which tyres suit sand.
| Inflator | Price | Flow at about 30psi | Free flow | Duty cycle | Max draw | Hose |
|---|---|---|---|---|---|---|
| ARB Brushless Twin Portable (CKBLTP12) | $1,575 | 176 L/min at 29psi | 260 L/min | 90% (spec sheet) | 90A | 7m |
| Ironman 4×4 MX195 On-Board (IAC012) | $799 | 130 L/min at 30psi* | 195 L/min | 100% | 65A | Fixed install |
| Bushranger Max Air III (55X23) | $425 | Not published | 72 L/min | 33% at 100psi | 30A | 9m coiled |
| Kings Thumper Max Digital | $299 | Not published | 300 L/min | Not published | 90A | 7.75m |
| Milwaukee M18 Inflator (M18BI0) | $279 (tool only) | Not published | About 40 L/min | 33% at 80psi | M18 battery | Short onboard hose |
Prices from ARB, Ironman 4×4, Kings and Repco, checked 13 October 2026. Specs from manufacturer pages and spec sheets. *Ironman's body copy also quotes 130 L/min at 40psi.
Buy for the worst day, not the average one: four big tyres, a tired battery and a queue behind you at the top of the ramp. If that day happens often, spend the money on the ARB or bolt in the Ironman. If it doesn't, the Bushranger will do. Just don't trust the biggest number on the box.
