how large a tank will i need to fill 4 35" tires from 5 PSI to 25 PSI?

Here's the deal;

I am gonna buy a Firestone 12 volt airbag compessor. The tanks are made in a variety of sizes ranging from ½ gallon to the largest being an 8 gallon.

I think I need:

air lines and fittings
adjustable regulater (to 110 PSI)
two 3 gallon air tanks with purge valves ( each 150 PSI max capacity)
12 volt heavy duty compressor.( duty cycled - .77cfm@60PSI/ .60@ 100PSI)
air chuck and recoil line
relay and switch.


have I forgotten anything?

is it really as easy as I think too pull this off?


1, Install compessor in engine bay.
2, install 2 tanks in truck bed.
3, join tanks
4, run air line from compressor, to regulater, to tank.
5, attach relay to 12v switched source with switch.

I looked into the A/C compressor thing and decided it was about the same work albeit cheaper but sacrificing my A/C.

Thanks for any help....
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My first choice would be a York a/c compressor if you can make room. What vehicle is this going in? www.onboardair.com can hook you up with a bracket for mounting it depending on the vehicle it's going in. Or build your own. I don't think your going to be happy with a compressor that was designed to fill air bags but if that's route you've dead set on doing get the biggest tank that you can fit. I would add a pressure relief valve to your list of parts. Do a search there is tons of info on this subject here and on the net.

Might want to check out www.onboardair.com and www.coloradok5.com the both have a lot of info on the subject.

don't need a pressure releif valve--- TIME to fill tires depends on volume output, not pressure !--ie; A cigarette lighter plug- in puts out the pressure ---- but no volume (15 mins.)!!!
I am useing one old R-134 tank------- with stock toyota a/c compressor, 1:45 to air up tires 5#/30#

i'm getting two things here so i'll put in my 2 cents on both.
first, it sounds like you are airing up the tanks and want to air up the tires off the filled tanks w/o the pump?? that would be a good sized tank, its a math thing and i dont do math, but you would have to find the volume of air at 25PSI for all four tires, then find how many gallons that volume is at say 150 PSI to get the size of the tank.
second, if you have an air compressor you dont need a tank to fill tires, the tank will give a boost of air(speed) only on the first tire and only until it equlized with the pressure you are working at, unless you let it refill everytime it equlized.
sooo, if you wanted to fill tires as quickly as possible you would need a tank big enough to air one tire on its own, and a compressor that could fill that tank in the time it takes you to move to the other tire.
thats not a big tank at 150 PSI, 3-4 gal.?? but it is a big compressor 50-60 CFM??

i hope that makes sense.

the flow rate is pretty low compared to A Yorks 4.0 cfm. That's why the tanks. I guess I would need to add a pressure switch that flips the compressor off at 100-110 PSI. That way I can turn the compressor on while I'm wheeling and let it air up the storage tanks.

When it comes time to air up...I'm guessing it will fill 2 tires before needing to fill the tanks agin.

The capacity is where it's at then? not PSI?

That would make the system I have planned no better than the garbage compressors you plug into your lighter. Damn!

Back to the drawing board.

It's a 4.0l V6 Ford Ranger BTW.

Thanks for the tips folks.

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