DIY multi tyre deflator/inflator

Tyre deflation and reinflation is something that is often done on a 4wd, yet there’s a lot of ways in which commerically available options aren’t ideal, especially for the Jimny. I decided to make my own out of random parts to let me deflate or inflate my tyres. Read on for why and how I did it, plus I’ll go through some of the more common (at least for Australia) options.

Sections

  • Options out there
  • Parts list
  • Building it
  • Using it

Commercial options you might consider

These are a bit more biased towards the deflation side: how you choose to reinflate depends a bit on your chosen compressor setup.

The manual option

The simplest option for deflation is something to poke the valve core down, and a pressure gauge to check where it is at.

Not really much else to say about this! If you are savvy you time how long it takes to get to the desired pressure on the first tyre and use a stopwatch to time letting down the other tyres to make it faster.

Pros: Simple to perform; minimal cost; not much to go wrong
Cons: Can be slow as you go back and check pressures; cannot do simultaneous tyres without multiple people

Valve core removers

This is maybe the next step up. Two options here, either just use a valve core removal tool and remove the valve for faster deflation…

… or use one that is self contained and screws onto the valve, ideally with an integrated gauge.

These can work well: they aren’t expensive, and generally are going to be faster than going back and checking the pressure multiple times although you do have the time taken to unscrew and rescrew the valve core in. I actually use tyre valve caps with an integrated valve core tool so I always have this option on the car.

Pros: Pretty fast per tyre; relatively inexpensive
Cons: Cheap ones can crossthread valve cores, ruining the valve stem; can only do one tyre at a time; doing it manually with just removing the valve core can involve you losing your valve core…

Automatic on valve deflators

These can get pretty fancy but basically are just some kind of device you screw onto the valve and let the pressure out to some set value. Some let you set a pressure relatively easily, some need calibration. I have experience with a few and all have in some way not worked just how I wanted which sucks, cause these otherwise would be ideal.

Pros: Can be fast (depending on the design); lets you do multiple tyres simultaneously; set and forget (mostly)
Cons: Plenty are not consistent with their settings if you can adjust them on the fly; can get quite expensive for reasonable quality one

Multi-headed deflators

This is where you get into the really fancy stuff. Two or four hoses to connect to tyres, integrated pressure gauge, usually with a connection direct to a compressor to make it easy to reinflate too. Examples of this might be the Maxtrax indeflate (4 tyre option: $329 rrp) or the MORRFlate quad (also 4 tyres: $315 rrp).

These are great, but they are not cheap (as per the above) and generally the hoses are way longer than you need on a Jimny. A lot also don’t seem to have a way to do front and rears differently, which is needed if you’re heavily loaded at the back or need different traction requirements (e.g. go a bit higher on the front if you’ll be turning under power in deep sand to avoid popping the tyre bear, and the extra traction with lower pressure at the rear will give you grip for longer)


What I’m after

Ideally, I want something that is:

  • Fast
  • Inexpensive
  • Lets me do multiple tyres together
  • Lets me set the front and rear tyres separately, or just equalise all 4 together
  • Has hoses that can be reused if something goes wrong (e.g. plugged direct into compressor)
  • Hoses are a bit more nicely routed to not be a mess around the car
  • Links in nicely with the ARB onboard compressor I have for inflation

This resulted in the following design concept, laid out on the car to see what I’m thinking about hose routing.

A downside of the way I’ve chosen to do it is the hoses are a bit less neat than if I didn’t want to do the front and rear separately. Most commercial ones have a hose going left and a hose going right, and if they are a 4-way deflator/inflator then they’ll split off the front hoses to go to the rears. I didn’t want to have to put valves to go to the rear inline in those hoses, and I also didn’t want the annoyance of 4 valves on the manifold either.

I also wanted to make it relatively compact so I used a cheap and small gauge. I generally like using a really nice tyre pressure gauge I have so the other option here would have been to fit a Schrader valve and just read the pressure using my normal gauge – but I wanted to get to read it continuously. This is, after all, entirely around deflating and inflating when on the road so near enough is good enough.


Parts list

Because I wanted this to link into the ARB compressor, I needed to find the compressor fittings that are already used for the ARB inflation kit. Annoyingly these are not the Nitto or even the European standard fittings. ARB for some reason use US industrial standard fittings which are different again. This added some complexity as I could only find them in NPT threaded fittings. This meant I had to get NPT not the more common BSP threads for the air fittings which dictated things a bit.

I bought everything from aliexpress as it was cheap and easy, with the exception of compressor hose

  • Four way manifold. This was meant to be 1/4″ NPT all around but turned up with 2x 1/4″ NPT and 2x 3/8″ NPT
  • 2x male, female, female 1/4″ NPT y-adapter
  • 8x 1/4″ NPT to 3/8″ (10mm) barb fittings
  • 4x lock-on air chucks for valves, 1/4″ NPT female air fitting
  • 3x 1/4″ NPT inline air valve
  • Hose clamps to suit compressor hose
  • 3/8″ compressor hose (bought from a commercial store here, lopped the ends off). About 10m would do it, but I bought 20m to be safe.
  • Small air pressure gauge, NPT fitting. Turned out I ended up with a 1/8″ BSP fitting on this one but got a 3/8″ NPT to 1/8″ BSP reducer bushing and that made it fine
  • Air fittings to suit the compressor – both male and female, 1/4″ NPT threads on these

Total cost of all of this was $108 including shipping the bits from China from aliexpress. The reason for using air fittings on the various bits is so I can pack it all up more neatly: If I also use a male air fitting on one end of the hose to the tyre with the tyre valve fitting on the other end, I can also potentially just connect that hose directly to the compressor on the bullbar. This means in the case of something going wrong I have some kind of a backup plan to fill the tyres up.


Building it

The building part is really pretty simple, just screw stuff together really.

I generally hate using thread tape, so permatex pipe sealant in a tube it is.

I plan to use nicer hose clamps at some point but worm drive ones do for making it work.

It’s really annoying with cheap parts to get the valves to line up so I just did my best while also making sure the seal. Probably the thing to do here would be using some rotatable swivel fittings to allow you some freedom on it.

The dump point is an air fitting so I can just connect a normal air hose, including the ARB inflation kit hose. This means I can use a longer hose and go fill up someone else’s Jimny off my car relatively easily, although I plan to carry a shortish hose that means they just have to park nose first to my car and then it’ll all fit ok.


Using it