I decided early on that I wanted onboard air for the Defender. I wanted this for airing up after a day on the trails but also in case I ended up with air lockers (more on that later). My original plan was to simply put a Viair compressor like I have in the van but once I started looking into the ARB compressors I was sold. They are small, they have a couple of difference sizes, they can power air lockers, and they come with a nice wiring harness. Initially I was interested in ARB’s larger compressor but the size held me back. I ended up going with their most popular compressor the CKMA12. It can handle tire inflation easily but it also has some ports to add solenoids for two air lockers. I also liked how flexible it was for the installation. You can twist the mini air tank and compressor body to get it to fit just about anywhere.
Defenders are short on space, but there is one area that just about every Defender owner installs an air compressor and that is under the passenger seat. Both of the front seats sit on a metal box which makes it rather easy to hide some gear. The driver seat has the car battery and I went and filled the rest of that space with an aux power tray. If you are interested in that project read more here. The passenger seat box holds the OEM jack but is largely empty. In 95-97 NAS (yes I know 96 was not a real year for Defender NAS imports) the passenger seat box also holds some OEM wiring, but in my 94 there was none so I had the entire space to play with. I decided to mount the air compressor there, bolted it to the floor and wired the switch to my switch panel I created on my center cubby box. I then ran an air line out of the box under the car up to the front bumper where I installed a quick disconnect for easy tire inflation. I will be able to add more air lines later for the lockers.
While it is easy to simply have a portable air compressor for tire inflation I am happy I spent the time and money to get a permanent onboard air setup. The hardest part was figuring out where I wanted to run all the electrical and air lines, other than that it is a quick and easy install. And for you Jeep people, it is even easier because ARB makes mounting brackets specific to your truck (as always Defender owners have to do it the hard way).