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Not ready for on-board air yet. Can you recommend a good portable compressor, whether it be battery or "cigarette lighter" type? I've had 2 recommendations for the VIAIR 77P, but would like some more opinions. Not looking to spend a bunch either.
 

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First question, what elevation are you at, wheel at? If you're a flat lander there's a lot of relatively cheap options BUT the performance sucks when compared to other options. Personally, I'd run a CO2 setup. A 10 or 15# tank can be purchased from any liquor store, my 15# filled was $75. A regulator from a welding shop $30-$50. Then a good coil hose, with air chuck and lock on fitting. You will need to make a shut off switch to use the fitting I put in the link but they are awesome! These simply lock on the valve stem and pull off. When airing up you simply snap it on the valve stem, turn on the air, and air up...nothing to hang on too. A 10# tank will easily fill up 35's from 6psi to 30, 2-3x's. And you can run air tools also.

http://m.opentip.com/search.php?cPa...1ob0m-YqfN-M-dhl06dhjXFJSVYihHyhoCTmMQAvD_BwE
 

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Some like CO2, some don't. I'm one of the don'ts.

There is no question that CO2 is fast. While it is possible to piece together a system on the cheap, as a practical matter expect to pay $200 and up for a pre-assembled system. [One good source is Instant Air Supply.] Refills are possible at welding supply stores and fire extinguisher supply houses, and many homebrew stores.

What I don't like about CO2 systems are the space they take up in a rig, that the tanks must be stored/used upright, that there is no good way to know how much is left in the tank (i.e., plenty of pressure until empty and then suddenly zero pressure), the ongoing cost to refill the CO2 tank, and having to remember to fill it.

For most people a quality portable 12v compressor is all they will ever need. Sure it will be slower than CO2 or a permanently mounted belt driven compressor, but what's a couple of extra minutes at the end of a day wheeling when everyone is packing up for the trip home and regaling each other with stories of the day's adventures? Moreover, 12v compressors don't need refills.

The key is not to cheap out or buy an underpowered unit. Yes, many people have used one of the ubiquitous $50 "little red Chinese compressors" for years without issue, but just as many have had their cheap compressor crap out after only a few uses.

In my opinion, Viair markets some decent portable compressor kits that are good values. For 33-35" tires, I recommend the Viair 400P. It pumps more cubic feet per minute @ 40 psi than most portable 12v compressors, which means that you can air up at least 8 35" tires from 12-35 psi before having to be concerned about duty cycle. It is currently available on Amazon for $139.97.

That's my two cents.
 

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We have 2 Jeeps, and wanted a portable compressor we could move between both. We tried a cheap 12v cigarette adapter one, and it was horrible. It was loud and underpowered, and the pressure setting never worked. We returned it and after a one star review the seller sent us a free one as an apology.

Then I got the Viair 400p. This thing is amazing. It's even quieter than the cheap one, and way easier to use. The company has excellent service, too. I bought it when it was around $250 and consider it worth every penny. For the current price it's a steal.
 

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Honestly a Vlair isnt much more that you will be spending on CO2. 2 of my buddies run the cheapo chinese compressors. They have been using them for a few yrs now.
 

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How much use does that give you?
Is my newbness showing? :happyyes:

It's left over from my rallycross days. Haven't used it for my Jeep just yet. Figured since I'm still stock and on 32's, I won't be airing down a lot for easy/moderate trails, so that would get the job done.

Maybe not so much? :banned:
 

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Is my newbness showing? :happyyes:

It's left over from my rallycross days. Haven't used it for my Jeep just yet. Figured since I'm still stock and on 32's, I won't be airing down a lot for easy/moderate trails, so that would get the job done.

Maybe not so much? :banned:
At least you said Jeep and not car lol
 
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For those of you that are new to off roading and airing down and up. Everyone's suggestions work for THEM and may not work for you. A flatlander in FL may be just fine with a cheap $50 pump, take that same pump to the Rockies and you'll quickly realize that the thin air dramatically reduces the same pumps efficiency!
Simplified, You may be a great runner at sea level and suddenly you get to 7000'+ and you feel like you've been chain smoking your entire life!

Now , there's the group that says,"why are you in a hurry to air up" or "I sit and BS about a great day of wheeling while I'm airing up". If that's their position fine but small air compressors are NOT meant to run continuously, they have very specific DUTY CYCLES. What is a Duty Cycle and why do I give a crap?? Glad you asked:

Compressor Duty Cycle: Duty cycle refers to the amount of time a compressor can be operated in a given time period, at 100 PSI, at a standard ambient temperature of 72oF. Duty cycle is commonly expressed in percentage format. The higher the percentage, the longer the run time. For more frequently asked questions on duty cycle, see Viair FAQ Page.

Duty Cycle Reference Chart
Duty Cycle: 100 PSI @ 72F Max. Run Time / Min. Rest Time
10% Duty Cycle 3 Min. On / 27 Min. Off
15% Duty Cycle 6 Min. On / 34 Min. Off
20% Duty Cycle 8 Min. On / 32 Min. Off
25% Duty Cycle 10 Min. On / 30 Min. Off
30% Duty Cycle 13 Min. On / 30 Min. Off
33% Duty Cycle 15 Min. On / 30 Min. Off
100% Duty Cycle Continuous Duty @ 100 PSI @ 72F

Think about these numbers for a minute, 10% duty cycle runs for 3 minutes then you have to WAIT 27 MINUTES until you can turn it back on! It's highly unlikely that your going to air a single tire up in 3 minutes but let's say you can. Air up 1 tire..........wait.........27 minutes, air up 1 tire (3minutes) ...........WAIT.............27 minutes, air up 1 tire (3 minutes) WAIT 27 minutes, air up 1 tire...let pump cool before putting back in your Jeep. Starting to get the big picture yet? Is that cheap $30-$50 pump so cheap after all? What is your time worth?
So you say, "I run mine nonstop and have never had a problem...UNTIL you do and your pump overheats and dies and now you're stuck with 1-4 tires not aired back up.

Correctly plumbing a small tank can help make a small pump more effective BUT you ALWAYS get what you pay for! Hopefully this helps some of you understand cost vs efficiency.
 

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. . .Compressor Duty Cycle. . . refers to the amount of time a compressor can be operated in a given time period, at 100 PSI, at a standard ambient temperature of 72oF. Duty cycle is commonly expressed in percentage format. The higher the percentage, the longer the run time. For more frequently asked questions on duty cycle, see Viair FAQ Page.

Duty Cycle Reference Chart
Duty Cycle: 100 PSI @ 72F Max. Run Time / Min. Rest Time
10% Duty Cycle 3 Min. On / 27 Min. Off
15% Duty Cycle 6 Min. On / 34 Min. Off
20% Duty Cycle 8 Min. On / 32 Min. Off
25% Duty Cycle 10 Min. On / 30 Min. Off
30% Duty Cycle 13 Min. On / 30 Min. Off
33% Duty Cycle 15 Min. On / 30 Min. Off
100% Duty Cycle Continuous Duty @ 100 PSI @ 72F
The numbers @Sinister6's duty cycle reference chart are slightly different than Viair's most current chart, which can be found at VIAIR Corporation - Tech

ONE HOUR DUTY CYCLE
(100 PSI @ 72° F)
MINUTES ON /MINUTES OFF

9% Duty Cycle 5 Min. On / 55 Min. Off
10% Duty Cycle 6 Min. On / 54 Min. Off
15% Duty Cycle 9 Min. On / 51 Min. Off
20% Duty Cycle 12 Min. On / 48 Min. Off
25% Duty Cycle 15 Min. On / 45 Min. Off
30% Duty Cycle 18 Min. On / 42 Min. Off
33% Duty Cycle 20 Min. On / 40 Min. Off
50% Duty Cycle 30 Min. On / 30 Min. Off
100% Duty Cycle 1 Hour Run Time
Note that these run times are calculated at 100 psi, almost 3x the typical 32-35 psi street pressure for stock size tires. For those of us running larger tires such as 35's street pressures are usually even less, in my case 26 psi and in @Sinister6's case 25 psi, approximately 25% of the duty cycle rating pressure of 100 psi.

What this means in "real world" terms is that a Viair compressor with a 25% duty cycle can run longer than 15 minutes at typical inflation pressures before requiring cool down, and a 33% duty cycle compressor such as the 400P can run longer than 20 minutes. How much longer depends upon many factors and would require some computations and experimentation.

I can fill my 35" tires from 12 to 26 psi with my Viair 400P (rated at 1.86 cfm @ 30 psi) in a little over 2 minutes per tire and am typically finished airing up all four tires in 10 minutes or less. With my 33% duty cycle I can still fill all four 35" tires on another rig before I hit the 20 minute time limit for operating at 100 psi. However, since I am operating the compressor at 25-26 psi rather than at 100 psi, in reality I can fill up the tires on a third rig (and maybe more) before I need to shut down the compressor. Since I have had only one occasion to fill more than 8 35" tires in one session, the 33% duty cycle of my 400P is plenty for my purposes.

CO2 is popular in Colorado with its higher altitudes because altitude (i.e., lower atmospheric pressure) doesn't affect the performance of a CO2 system like it does an air compressor. I agree that the difference in high altitude performance between CO2 and one of the cheap, low output compressors would be dramatic, however I typically wheel at altitudes of 7,500' and total air up time with my 400P is only a few minutes longer than at lower elevations, not enough to interest me in going to CO2.

@Sinister6 is absolutely correct that one needs to weigh the pros and cons of a particular tire inflation system in the context of one's unique needs and performance goals. But don't let duty cycle considerations scare you away from a 12v compressor. There is nothing inherently inferior about a compressor with a 25% or 33% duty cycle (many of which have greater output ratings than similar compressors with 100% duty cycles). You also need to consider compressor output, fill time for your tires, quality of construction, warranty support, continuing costs of operation, the space it takes up in your rig, portability, etc.

Whichever system you choose, don't let a low price be your determining factor. As Judge Milian on the People's Court likes to say, "We have a saying in Spanish, 'Lo barato sale caro'. The cheap comes out expensive."
 
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37psi on a 32" tire is way too high. And 25psi isn't even close to airing down.
The 37 PSI is on the sticker on the door panel as the recommended pressure for the 255/75R17 tires.

As far as only airing down to 25 PSI, I new to airing down and didn't know how far to go. Can I ask what your recommendations are? I would prefer not going so low as to have the tire come off the rim.

Thanks for the info ahead of time.
 

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That's still too much air pressure for daily driving.

I air my 33s down to 8psi and have never lost a bead. I might even go lower. Normal driving for me is 26psi.
 

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I'm using 10-12 psi
 
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