Tire Fill tank

Okay, I want to run an idea by you all.

I've been looking for a way to air up my tires before heading back home. I am currently sitting on some 31" BFG ATs, which are normally only aired down to 15 at the lowest. I was thinking of using an old paintball HPA tank. I've had it for a couple years and I have all of the necessary regulators/air adapters already sitting around.

The tank is a 68/45 tank, which means it has 68 cubic inches at 4500 PSI. Now, the 4500 PSI is a bit optimistic since most fields will only fill to about 4000 PSI. I normally fill it before leaving the field after I play, so it will be filled before I go wheeling at no additional expense. Based on some rough calculations I figured that my tires contain roughly 2800 cubic inches and I normall fill them to about 35PSI, so I only really need to put in 20PSI per tire after wheeling.

With some minor and rather primitive calculations I figured that I could fill one tire of that volume to about 97PSI if it started at 0. So, it would seem quite feasable to be able to fill 4 tires an additional 20PSI to get them back to street pressure.

I'm basically asking if anyone can confirm this for me, or if anyone knows anyone that has done this. My basic motivations are the cost and portableness (the entire setup would be very compact). Thanks folks!

Moderators - I couldn't think of what section to put this in, if there is a better location would you please move it?

Does your A/C work? If not you can do an A/C to OBA conversion. Search it to find multiple write ups.


Your idea should work by you will always be worrying about running out of air. On board air let's your a/c compressor fll it up whenever you need it.

My AC does work and I want to keep it haha. I had thought about onboard air, but decided against it. A lot of the reason for this small air tank idea is that I already have all of the parts.

I just have a little portable air compressor.

i just made my onboar4d air, stock ac compressor fills a r-134/a tank i got from work and purged, regulator is built into tank, compressor fills the tank to 100psi easily, however the local tractor supply has portable tanks on sale for 15 bucks, and i think thats a bit more reliable so ill be getting one of those this weekend, all i need now is a pressure switch to turn the compressor off at a set pressure

My uncle made a custom bumper for his CJ7, the bumper is hollow and is used for an air tank. I always thought that was a fun idea...

I can't offer you a definitive answer based on a mathematical equation but it seems the tank would not hold enough volume, even at that pressure, to inflate 4 tires to 20 PSI. Please post up if you try it.

FallibleXJ said:

Okay, I want to run an idea by you all...

Click to expand...

It's a good idea, miniaturizing the airtank, using what you already have. I'd definitely say it's worth pursuing.

My only concern is that 4500psi is a whole lot of pressure.

You seem comfortable with it, but that's a lot more than I'm used to dealing with. Makes me a little nervous...

Robert

If you are good at fab work or know some one who is then have them make your sliders, bumpers air tight and with nozzles for air lines. A lot of people do this whit there trailers, the large ID tubing can hold quite a bit of air.

you will just want to make sure that the pressure is correctly regulated so 4000psi is not going directly into the tire but has a step down area to drop the pressure to below 200 when seen at the valve of the tire.

WrenchMonkey said:

It's a good idea, miniaturizing the airtank, using what you already have. I'd definitely say it's worth pursuing.

My only concern is that 4500psi is a whole lot of pressure.

You seem comfortable with it, but that's a lot more than I'm used to dealing with. Makes me a little nervous...

Robert

Click to expand...

I still get a lil nervous while refilling my tank, however, I've been playing paintball for about four years now and filling my tank ever since and not had a problem yet.

With the regulators I have sitting around I can regulate the output pressure down to about 100PSI. Which is low enough for most common plumbing pieces needed for the fill nozzle (can't think how else to phrase it).

Magus2727 said:

If you are good at fab work or know some one who is then have them make your sliders, bumpers air tight and with nozzles for air lines. A lot of people do this whit there trailers, the large ID tubing can hold quite a bit of air.

you will just want to make sure that the pressure is correctly regulated so 4000psi is not going directly into the tire but has a step down area to drop the pressure to below 200 when seen at the valve of the tire.

Click to expand...

I've thought about this, I was actually having the conversation a couple days ago with a buddy of mine who is rebuilding the bumpers for his XJ as air tanks.


No one seems to have any strong objections to the plan, so I think I will go ahead and try it once I get the chance. Might rig it up this weekend.

I wondered about the CO2 tanks they sell at lowes for the portable air tools.

FallibleXJ said:

With the regulators I have sitting around I can regulate the output pressure down to about 100PSI. Which is low enough for most common plumbing pieces needed for the fill nozzle (can't think how else to phrase it).

Click to expand...

I always called it an air chuck.

But sure, if you can get it down to 100# -- safely -- you'll be good to go.

I'd just worry about whatever fittings live between that little tank, and the regulator. If they're up to it, cool!

Robert

what about having about 100 of those little one time use CO2 bottles for bike tires? That would take a while for 33's.....

This is what I did. I found this on another forum


You can put together a DIY 10lb tank setup for less than $130 dls plus shipping.
New 10 LB aluminum co2 tank on ebay $73
Hyperflo Co2 Regulator Wheelersoffroad.com $38
25ft reinforced Pneumatic hose harborfreight.com $9
Brass Quick Coupler kit ebay Set $4
Tire inflator chuck $3


The only thing i changed was i got a used co2 tank in town at Universal Cylinders for 35 or 45 IIRC.

WrenchMonkey said:

I'd just worry about whatever fittings live between that little tank, and the regulator. If they're up to it, cool!

Click to expand...

The regulator on the tank has an output pressure of roughly 700PSI (800 at peaks). From there it goes to an on/off ASA (Air Source Adapter) which adapts it down to 1/4" NPT fittings. From there I will be plumbing it into the regulator which also accepts 1/4" NPT. So the only piece of piping that will be exposed to the the higher pressure, being 800 PSI, will be a short nipple. Even the brass nipples, at that small diameter are rated that kind of pressure.

Magus2727 said:

what about having about 100 of those little one time use CO2 bottles for bike tires? That would take a while for 33's.....

Click to expand...

That would be a very expensive method haha. I also have a stack of those little 12 gram cartridges, they cost about $0.50 a piece when bought in bulk. 100 a tire would be about $50 a tire haha.

Mutant_Xj said:

I wondered about the CO2 tanks they sell at lowes for the portable air tools.

Click to expand...

that would work just fine! I use a co2 tank now, it's way faster then an ARB compressor! I can fill 8 tires to 2 from an ARB!

The real problem with any low pressure - 100psi - system is that bumper tanks don't hold enought to fill four decent tires. You have to use the onboard air pump regardless. And like the OP, I don't want to 1) change out the a/c - it's been 90+ daily for a week already, and 2) the expense of building a bumper and constantly hauling the dead weight around 30 days out of 31.

Really, onboard air is a bit extravagant on a daily driver. For a dedicated trail machine, go for it. Daily, we need to figure whether the trade-off of gas mileage at the rising prices is justifiable.

Certainly, hi pressure sources are unique, and if available, why not? MOST of us don't have that as an option.

And converting a compressor to onboard air isn't the best. I talked to a a/c shop owner Wednesday and asked him. A/C compressors are just another hi pressure low volume supply, not unlike the 12V ones sold to inflate tires.

What we really need is volume, not pressure - like what 18 wheelers use to supply air brakes. Another alternative might be to use a compression checker plumbed to an air line on the #2 plug and disco the injector. Or just buy a decent hi volume pump with a 12VDC motor on it's own skid.

It seems everyone complains about mileage after all the mods, kinda like the guy with a pickup camper who drove it that way all year. It was great for the two weekends he used it, but sure ate up his gas budget 50 weeks a year - and he had to take it off to cut firewood anyway.

Again, permanent air is great if you use it, but too many of us drag dead weight most of the year and don't need it.

300$XJ said:

that would work just fine! I use a co2 tank now, it's way faster then an ARB compressor! I can fill 8 tires to 2 from an ARB!

Click to expand...

Maybe faster,but not an "endless" supply like OBA.By the time I do all the other "get ready for the trip back" things,all my tires are full and I can start on "yours"!!:wave1:

get the new warren winch that also has a adapter for an Air line and is able to run Air tools....

RCP Phx said:

Maybe faster,but not an "endless" supply like OBA.By the time I do all the other "get ready for the trip back" things,all my tires are full and I can start on "yours"!!:wave1:

Click to expand...

yep your right it's not endless, but I've had the tank since last october and the needle has barely moved! so it's pretty endless! just gotta plan ahead if its low and get it filled. I have prolly aired up 60 or 70 tires and it's still going! no issues with it on my end!