To get the most out of your 4WD action make sure you have the best tyre pressure for the conditions you are driving in. Let’s face it though, who wants to sit in the middle of nowhere pumping their tyres like its 1927! Portable air compressors are a great way to not only lower your tyre pressure to the right level and then re-inflate them when you’re back on tarmac! Buying the right air compressor depends on use, weight and a whole bunch of factors, let’s take a look at a few!
Why do you need an air compressor when going offroad:
An air compressor is essential when tackling harder obsticles like beach driving or rocky tracks. Letting the air out your tyres means they will have more surface traction and grip. Knowing the right PSI to deflate to will take some testing but as you gain more confidence, you will want to tackle harder obstacles which means lower PSI. It also means finding the right aircompressor to suit the job of airing back up before hitting the highways. 4x4 air compressors are different from normal air compressors you might find on job sites or panel beaters. They are compact and are designed to work off a 12v power source.
What to look for:
The first thing you should always look out for is flow rate. The flow rate will determine how quickly the 4x4 air compressor will be able to inflate a tyre. For example an air compressor with a150PSI/ 1034kPa output can easily inflate the average 4x4 tyre (205/60R16) in around 2.5 minutes. There are many other factors that determine the quality of a 4x4 air compressor such as bore, stroke, rpm, and internal design. Another well known fact is that air compressor get hot and if the internals over heat you can seriously damage the air compressor. So be sure to keep it in the open when using it and if it feels like it's going to melt, leave it for a while. High temperatures can impact a compressor’s ability to work as well as reduce its overall lifespan, so look for models that can deal well with heat. Units that include insulation over the hose to compressor connection will protect against burning your hands when disconnecting the hose.
This is not ideal so you want an air compressor that can handle the job, prefferably one that has thermal overload and circuit breaker protection. It’s also a good idea to familiarise yourself with the term 'duty cycle' in a 4x4 air compressor. Duty cycle is the amount of time the pump is actually working vs the amount of time it needs to cool down. In an ideal scenario you'd want to be able to perform a continuos flow of air but some smaller air compressors need a few minutes inbetween. When your in the middle of the desert covered in flies and just want to get back into the airconned cabin, you might want to think about upgrading.
Here is a chart to make it a little easier to understand what 'duty cycle' means. This will varying depending on weather and temperatures:
|Duty Cycle @ 100psi and 22°C||
Max. Run Time / Min. Rest Time
|10% duty cycle||3 min ON / 27 min OFF|
|20% duty cycle||8 min ON / 32 min OFF|
|30% duty cycle||13 min ON / 30 min OFF|
|100% duty cycle||Continuous duty @ 100psi and 22°C|
Compressors differ in price a lot, with portable options ranging from under $100 to over $1000. The more you pay for an aircompressor does not actually mean better quality. Choose the right air compressor for the situation. Bigger and faster does not always mean better. Depending on the tyres you have on your 4x4, an air compressor may only be able to fill them at a certain speed.
Space is always at a premium when you are heading off on an adventure, making it a smart move to get the smallest compressor that will suit your needs. A 4x4 aircompressor also needs a 12v power source so it's a good idea to check just how many amps it will draw in an hour. You may need to sacrafice on power and speed to conserve battery if you are only running power off the starter battery.
The less weight you are carrying in your 4WD the better it will handle and the longer your tyres will last. You will also appreciate having a lighter compressor to haul in and out of your vehicle every time you need to inflate your tyres.
As with any major purchase a good warranty will provide you with backup if anything goes wrong. If you are having trouble choosing between two compressors go with the one with the best warranty.
Having a decent carry case for your compressor can definitely be handy, and if you tend to be hard on your gear look for a case that provides a little extra protection.
The 2011 Australian 4WD Action No Bull Test Air Compressor Comparison:
Australian 4WD Action conducted extensive testing on 24 series-wound 12V electric units, comparing them based on all major characteristics. Tests were done using a 285/75/16 Cooper STT tyre mounted on a LandCruiser steel rim and included inflating tyres from 0 to 40psi, from 16 to 40psi as well as an epic endurance test. The results were broken down and analyzed to determine the most consistent and best overall performer 4WD ACTION WINNER! – Dr. Air Pro Flow 150LPM by Haigh Australia (also the best overall performer out of all compressors tested!)