Best Air Compressors for Airing Down

Airing down to the mid-20s or lower is the cheapest traction upgrade you can make on dirt and sand, but only if you can air back up before the highway. Getting four big tires from trail pressure back to highway pressure is a lot of air, and a small tire inflator is slow at it. Fill time comes down to airflow, so that is the number to shop on.

We list 30 compressors, from $69.25 to $1,379.95. Below, each one shows its airflow quoted from the listing when the maker publishes it (13 of 30 do). Nothing here is our own fill test.

The two numbers that matter

Airflow (CFM). This decides fill time. Look for the figure at a working pressure (some makers publish CFM at 0 psi, which flatters every compressor). Compare like with like.

Duty cycle. How long it can run before it has to rest, given as a percentage at a set temperature. A 100% duty cycle compressor can do all four tires back to back. A 30% one will make you wait, and it'll wait longer in July in the desert, because duty ratings are given at a test temperature.

Portable or onboard

A portable compressor sits in a bag and clips to the battery. It moves between vehicles, and nothing has to be wired. An onboard compressor bolts in and is wired to the battery through a relay. It's always there and frees space in the cargo area, and a dual-motor unit can run air tools and seat beads. If you have one vehicle and you air down every trip, onboard is the nicer way to live. If not, buy a good portable.

Portable compressors, by price

Viair Every Vehicle Carry® EVC31 PRO Rechargeable Portable Compressor

$69.25 $89.95 23% below typical price at VIAIR

• Portable: lives in a bag, clips to the battery
• Airflow (CFM) not stated on the listing

Bulldog Winch Portable Air Compressor, 100 PSI, 1.2 CFM, Automatic Shut-Off

$96.99 at Trail Recon

• Portable: lives in a bag, clips to the battery
• Airflow: “…Winch portable compressor is rated 100 psi at 1.2 CFM and fills tires up to 31 in. Set the…”
• Rated 100 PSI (from the name)

Ironman 4x4 AIR CHAMP PRO 5.65CFM - 12V Heavy Duty Portable Air Compressor

$199 at Ironman 4x4

• Portable: lives in a bag, clips to the battery
• Airflow: “…harsh conditions of off road travel. Pumping out 5.65CFM (160L per minute) at a maximum 150psi.…”

Overland Vehicle Systems Up Down Air EGOI Air Compressor System 5.6 CFM

$249.99 at Off Road Tents

• Portable: lives in a bag, clips to the battery
• Airflow: “…EGOI Air Compressor System 5.6 CFM W/ Storage Bag, Hose & Attachments…”
• Duty cycle: “…PSI maximum output with 120 PSI working pressure 75% duty cycle 24' coiled air hose It fits nicely in…”

ARB Brushless Single Motor Portable 12V Air Compressor

$869.95 at Trail Recon

• Portable: lives in a bag, clips to the battery
• Airflow: “…Single Motor Portable compressor delivers 4.59 CFM at 0 PSI and 3.10 CFM at 29 PSI, with…”
• Duty cycle: “…3.10 CFM at 29 PSI, with active cooling and a 90 percent duty cycle. It reaches 150 PSI and protects…”

Onboard compressors, by price

Bulldog Winch Light Duty On-Board Compressor, 130 PSI, 1.3 CFM

$109.99 at Trail Recon

• Mounts under the hood or in the bed (onboard)
• Airflow: “…It is rated 130 psi, replenishes a tank at 1.3 CFM and has a 1/4 in NPT leader hose with…”
• Rated 130 PSI (from the name)

Viair 400C Compressor

from $346.75 at VIAIR

• Mounts under the hood or in the bed (onboard)
• Airflow (CFM) not stated on the listing

ARB Brushless Single Motor Onboard 12V Air Compressor

$559.95 at Trail Recon

• Mounts under the hood or in the bed (onboard)
• Airflow: “…Single Motor Onboard compressor delivers 4.59 CFM at 0 PSI and 3.10 CFM at 29 PSI at a…”
• Duty cycle: “…4.59 CFM at 0 PSI and 3.10 CFM at 29 PSI at a 100 percent duty cycle. The brushless motor removes the need…”

Don't forget a deflator

Letting air out with a tire gauge is slow and uneven. A deflator sets all four to the same pressure. We list 4, from $30 for the Synergy Manufacturing Synergy E-Z Analog Tire Deflator.

Airflow and duty cycle are quoted from each listing's own description. See all air compressors and deflators, and our recovery board guide.

How to choose a compressor

Size it for your tires. Bigger tires hold more air, so they take longer to refill at the same airflow. A small inflator that's fine for a sedan can take a very long time on 33s or 35s. If you run big tires or air down often, look for a compressor with airflow published at a working pressure, and a high duty cycle.

Read the airflow number carefully. CFM at 0 psi is the most flattering number a maker can quote. Airflow drops as the pressure rises, and you're filling tires to 30–40 psi, not 0. The best listings give both. When a listing only gives one figure, treat it as a best case.

Duty cycle is about heat. A 50% duty cycle means it should rest as long as it runs. Duty cycle is rated at a test temperature, and on a hot desert afternoon a compressor overheats sooner. A 100% duty cycle compressor can refill four tires without stopping.

Power. Bigger compressors draw a lot of current and clip straight to the battery. Run the engine while you inflate so you're not draining the battery. Onboard units need a relay, a fuse and proper wiring; plan for that cost or install time.

Portable or onboard

A portable compressor lives in a bag and can move between vehicles. An onboard compressor is wired in and always there, and can feed air tools or an air locker. If you air down most trips and have one vehicle, onboard is worth the install. Otherwise, a good portable covers it.

What else you need

• A gauge you trust. Built-in gauges vary. A separate low-pressure gauge is worth having, especially for sand pressures.
• A deflator. It sets all four tires to the same pressure much faster than holding a gauge to the valve.
• A long enough hose to reach all four tires, or the rear tires of a trailer, from where the compressor sits.
• Valve caps back on afterward. Grit in a valve core causes slow leaks.

What to avoid

• Running a compressor past its duty cycle. It will overheat and may shut down or wear out early.
• Driving on aired-down tires at highway speed. Air back up before pavement and rocks.
• Comparing 0-psi CFM against CFM at pressure. It's not the same number.
• Clipping a high-draw compressor to a small battery with the engine off.

Airing down, briefly

Lower pressure lets the tire spread out for traction in sand and over rock, and it smooths washboard. How low depends on the tire, the load and the terrain. For deep soft sand, the Park Service at Great Sand Dunes says to reduce to about 20 psi and reinflate before rocks. Our southern Utah airing-down guide has the details and the safety notes.

FAQ

What CFM compressor do I need?

More is faster. For 33-inch and larger tires, look for a compressor that publishes several CFM at a working pressure (not just at 0 psi) and a 100% duty cycle.

Portable or onboard compressor?

Portable if you move it between vehicles or don't want to wire one in. Onboard if you air down often in one vehicle or want air tools.

Does duty cycle matter?

Yes, especially in heat. A low duty cycle means stopping to cool down partway through four tires.

Do I need a tire deflator?

It's not essential, but it makes airing down faster and more even, and costs less than most gauges.

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