Air Tank - Compressor

I have a 22 litre tank from one of those el-cheapo $99 throw away bunnings type compressors. I have fitted it under the left rear seat in the navara against the chassis rail with the blue tongue behind the seat on a BIG dob of silicon. It does take about 10 minutes to get to about 100 psi and will take 5 to 8 minutes to pump 4 big tyres from 14 to 28 psi. with the blue tongue running. Rus.

I am looking at a 9 litre tank and using a A R B air pressure switch which means I run the tank at 100 PSI and the compressor cuts back in at 75PSI so I think that kind of capacity should do the tyres ok.
I hope people answer you and agree with me or shoot holes in my theory before I put the tank in.

Would obviously depend on what size the tyres are on the Navara & to what pressure the 12 volt compressor cuts out at but as a rough example my 9 litre tank pumped up to 100 psi will raise a 285/75/16 from around 25 to 35 psi.
At a guess I'd say a set of standard Navara tyres would need around a 50 to 60 litre tank to do what you want. Personally I'd save the space & spend the time & money buying a 3 cfm+ compressor instead.
Cheers Craig...........
3 cfm Big Thumper / 9L tank.

I think this was covered in a previous post I can not find.

From memory, I think I worked out that a 235/85/16 (32" OD) is about 80 litres at one atmosphere (normal air pressure, or the valve out and tyre laid on the ground), so to increase pressure to 2 atmospheres (about 28 psi with the valve in!), would take about another 80 litres, or to 3 atmospheres (40 psi), another 160 litres.
A 20 litre tank at 100 psi (7 atmospheres) would hold about 140 litres.
(Yeah I know, you would only get 6 atmospheres out).

Plus there is the air the pump is putting out air as well while you are filling.
1 cfm is about 35 litres/min.
Rough figures, but gives you the idea.

So four tyres, if they are 235/85/16, from 20 to 32 psi (12 psi = .85 atmos), would be 4x0.85x80 = 272 litres. So about 2.25 of 20 litre tanks.
Either way you do it , you will have to sit and wait for the pump to catch up.
The tank will only save you the effort on the first two tyres.
Now if you went from 20 to 26 psi, the tank alone might cope with all four.

So remember to rework to suit your tyre size.

Some one going to check me on the maths? Think I got it right.

Just buy yourself a decent compressor , and have a beer while you pump up your tyres. If you have bought a decent compressor, you will not have to worry about being over the limit by the time that you are finished.

I had my spare tyre at 60psi and made a air transfer hose:
Site Link

For a tank, I use a 9litre Fire Extinguisher... I purchased a few air fittings to replace the tyre valve and the hose to a Jamec Quick connect. This and My ARB compressor (now Max Air) meant I could air up in seconds... Tank did 2 tyres and the spare topped up the other 2...

Steve

The other ready made tank on most vehicles is the bullbar.

Short lengths of hose to link the various sections of tube, will provide a reasonable tank. Not sure of exact capacity, it would vary from bar to bar. I know of people who have dome this and claim it to be very successful

I have also heard though, that it is not a good Idea to have a pressure vessel in a position where it could suffer impact damage.

Duncs.

Thank you everyone for your comments, in the end, I think I might continue to use the compressor, which pumps all tyres up within about 12 minutes.

I was trying to be lazy , thinking it wouldnt take very long with a tank.

What I might do though, for the caravan site, is at Super Cheap Auto they are selling 240v air compressors with tak for around 139 with lots of air tools and fittings.

Thanks again for the comments, much appreciated

another alternative that no one seems to have mentined here is dropping by a truck wrecker. Most turcks have air operated brakes, so yo should be able to pick and choose from an array of sizes/shapes etc to suit your needs, all of which are purpose built for compressed air and should have suitable fittings... Thats what i intend to do once I get around to it.. if for no other reason than to speed up the air up process. I have an ARB compressor fitted under th ebonnet,, as I approach where I will need to air up, I flick the compressor on and start to fill the tanke, then by the time I stop I should e able to save at least half the time to air up. Buying and fitting a tank shouldn't cost me more than I guess about $50 or so..

Keep us posted on how you go, I have read about that approach, but from the reads here, you still need a number of litres to pump up 4 tyres from 20 psi to 40,
as opposed to when you do it with the compressor