OK folks, here’s something we all know: The standard air pressure recommended by the manufacturer of your truck’s tires is fine for the pavement, but it’s way too high for off-road use. Out on the trail you’ll need lower air pressure for added traction in sand, mud, and rocks. Those conditions, as well as your choice of tire and wheel, will determine just how low you need to take your tire air pressure when you’re off doing what your vehicle was born to do. In sand you might need to run as little as 10 pounds of air pressure for the best flotation. But whatever air pressure you run, the real question is not if you’re going to get down to that pressure, but how you’re going to air back up once you hit the pavement again. (See Four Wheeler, May 2001, for more on air pressure, tires, and trails.)
There are several options for airing up at the end of the day. These include: a hand pump, compressed air or CO2, engine-driven compressors, and the ol’ reliable 12-volt compressor that runs off your battery. This latter choice is by far the easiest, as you can either clip the power leads to the battery or hard-wire it to your truck’s electrical system. The smaller units can even be plugged into your rig’s cigarette lighter. Unlike an engine-driven compressor, a 12-volt unit can be mounted anywhere you have space. They also have the advantage over compressed gas sources because, obviously, they don’t become empty. For the average ’wheeler a 12-volt compressor is definitely the best choice.
With this in mind we’ve tested some of the best and most available 12-volt compressors on the market. We’ve put nine of these blowhards up against the wall and beat them until they revealed their secrets. The result? As expected, the more you spend on a compressor, the more air you get. But wait, there also were some surprises. Take a look and see which of these 12-volt compressors is right for you.
Step By Step
Lock Em Up
The original ARB air compressor is the perfect air source for your ARB air locker. While $295 may seem like a lot for a compressor this small, you must remember that this includes all the wiring to operate one ARB Air Locker. A mere $172 will get you a portable ARB unit if youre just interested in occasionally filling your tires after a day on the trail. This unit is small and lightweight but it gets the job done, even if it does take six and a half minutes per tire.
The Currie compressor is the only military-spec unit of the lot, so if youre looking for a tough tool, consider this baby. This 100-percent-duty-cycle compressor is capable of moderate air-tool use. When combined with a 2-gallon air tank, it spun six lug nuts before pausing. However, the 100psi max gives it some limitations in this department. It took the Currie compressor only 3 minutes, 7 seconds to fill our tire.
Mama Bear Air
As the fairy tale goes, one was too big, one was too small, and one was just right. The Quick Air 2 is the midsize unit in the Quick Air line and were sure many readers will find that it is just the right size for their needs. This unit pulled 24 amps, filled our test tire in 4 minutes, 40 seconds and is priced at $250 for the hard-mount and $305 for the portable. All these figures are right in the middle of the spectrum. The portable unit includes a 25-foot nylon coil hose with clip-on air chuck, clip-end power cable, and an on/off switch, all in a steel case.
The Big Red Plus compressor might be a small unit with 20-percent duty cycle, but it has survived the Outback. This compressor clocked a lengthy 6 minutes, 39 seconds in our tire-fill test. It is offered in either a hard-mount or portable unit. The portable unit includes 25 feet of polyurethane coil hose, 10 feet of full-size jumper cables, a waterproof on/off switch, brass quick-release fittings, clip-on air chuck, and a pressure switch, all housed in a steel waterproof storage box. Hard-mount: $249.95; portable: $395.95.
The Trail Head compressor is the heaviest and the hungriest of the compressors we tested. The unit weighs 40 pounds and pulled an astonishing 200 amps. On the plus side, this thing is faster than a cheetah. It took only 1 minute, 22 seconds to pass our tire test and it filled a 2-gallon air tank in less than 15 secondstwice as fast as its nearest competitor. At $599 its the most expensive of the units we tested, but for that price youll get top speed and the ability to run air tools continuously. Imagine a shop compressor under your hood. Our test unit was a prototype, so some specs might change with production units.
Slow but Sure
The Quick Air was the slowest of all the compressors tested but it was the most frugal on power consumption, with only a 10-amp draw during our tests. Sure, 7 minutes, 18 seconds per tire is a lot of time to spend airing up at the end of the day but think of all the things you can get accomplished while airing up. You could wash the windows, eat a snack, and help your buddies fix their trucks. The real advantage of the Quick Air is its small size and proven reliability. Weve used a portable unit for years without a hitch. The Quick Air is available as either a hard-mount or a portable and is priced at $175 and $235 respectively. The portable unit includes a reinforced rubber hose with clip-on tire chuck, cigarette lighter power plug, and an on/off switch, all in a molded plastic case.
Fast for the Cash
With a fill time of 2 minutes, 50 seconds for our test tire, the Quick Air 3 was the second fastest at airing up. Sure, it only has a max pressure of 70 psi (not enough to run air tools or an ARB Air Locker), but if all you want to do is fill tires, this is your baby. At press time the only unit available was a hard-mount with a retail of $399, but a portable unit is planned.
Built to Last
The Extreme Aire compressor is the only unit with a large, washable K&N filter on the intake, which extends compressor life. With a 100-percent duty-cycle and 150psi rating, it took only 3 minutes, 5 seconds to fill our test tire. The Extreme Aire performed well in the air-tool test, too. It was able to spin eight lug nuts before pausing when combined with a 2-gallon air tank.
Free Accessories (almost)
The EZ-Air is a little unit at a little price. At $179 (hard-mount) and $199 (portable), the E-Z Air is another good choice for those on a tight budget. This compressor has the most economical accessory package of the lot and for just $20 more you get a 25-foot nylon coil hose with clip-on air chuck and integral pressure gauge, battery-clip-end power cable, and an on/off switch, all in a nylon case. An added feature is the deflation-locking mode, which allows for rapid hands-free air down.