If you've never had any type of onboard air system, you don't know what you're missing. And that's probably a good thing, because you would've kicked yourself years ago for not having it if you'd realized how useful it'd be to you. Pressurized air can be used for air-driven tools, to fill up tires, to run air lockers, to fill airbags, for compressed air to blow things off, and even to run air-powered margarita mixers. It will seat a tire for you should you blow a bead, and be your boon when you're in the middle of nowhere and in a dilemma.
But you have a few options of what type of air system to run, how to run it, and what accessories will make accessing your available air easiest. It'll take some brain time, but you can come up with some pretty trick air systems. We've seen guys running under-bed tanks with air couplers coming out the front and rear, an extra line to run a pneumatic locker switch, plus a hard line run to an air-driven blender.
Electrically driven air compressors are a great way to get some onboard air, without too much modification. They can be placed in almost any location and run to air tanks that will give a reserve for using air tools, filling airbags, or any other type of high-demand chore.
The 12-volt air compressors are nice for a number of reasons. They run off 12 volts, so you can use one on almost any vehicle made, and heavy-duty ones have a 100 percent duty cycle, which means you can just keep using them as long as you need. This MaxAir 4.0 unit comes with a stainless leader hose to run to an air tank, has an air output of 4.0 cfm at 0 psi, and requires no maintenance, not even oiling since it has a piston sheathed in a Teflon coating. The compressor will put out a maximum of 150 psi but this is not as important as the cubic feet per minute that it displaces. Example: a 3-gallon air tank filled to 150 psi will barely inflate one 35-inch tire, but a larger air tank, even sitting at a lower pressure, will have enough volume to fill the tire with some extra air to spare. Remember this when scouting for a new compressor: cfm is more important than psi!
The biggest drawback to an electrically driven air compressor? The amperage. At only 35 psi, the MaxAir will be drawing 30 amps from your battery. Step that up to 100 psi and you're grabbing 46 amps from your electrical system, and 60 amps at 150 psi! And that's not even that bad compared to some other electric air compressors that will suck as much as 150 amps while running. This is enough to cause a lesser battery some serious issues, so make sure you have a heavy-duty battery (preferably a deep-cycle sealed one) and your engine running and alternator charging, if possible.
There are two important aspects to look at when buying an electric air compressor: One being that it has some type of air filtering element-because you're going to be off-road, right? The other being that the compressor has a 100 percent duty cycle. This means that the compressor will run nonstop, as long as you want. Anything less than 100 percent means that you'll be stopping to let the compressor cool down before you're likely done with your work.
Carbon dioxide tanks have become very popular to have in vehicles over the last decade or so. They've been around for much longer than that, but the idea of having a portable air tank that you can carry to any job has become very appealing. They typically come in 5- or 10-pound tanks, and can fill more tires than your patience would handle. This unit from Powertank is just about the best you can get when it comes to CO2 tanks. It's typically a bit more expensive than other tanks, but it comes with an extremely nice regulator showing tank pressure and line pressure, along with a coiled air hose and tire inflator sporting a built-in pressure gauge.
The real advantages of this type of air system are that you do not have to wait for some compressor to air up, there are really no moving parts, and it can be pulled out of your truck and taken far away from any type of power connection.
Why CO2 instead of air or nitrogen? CO2 is a much denser gas than typical air or nitrogen, and is stored in the bottle in a liquid state under a massive amount of pressure. For an air or nitrogen tank to endure as long as a CO2 tank would, it would have to be at least three times the size.
The downside to CO2 tanks? When you run out of juice, you'll have to take the tank to a CO2 refilling station. And the regulators will freeze (cold) under constant use, requiring you to sometimes stop running your power tools and let things warm back up.