Airing down discussion

StG58

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Must be bored now that the rain has set in for real.

What PSI do you-all run when you air down?

I have 31x10.50R15's on 7" wide wheels. The TJ weighs from 3,300 to 4,300 pounds depending on loadout. So, aired up, it's 26 to 30 psi depending on my mood, motivation and the load. Aired down, I just drop it to 8 to 9 psi and call it good. Sand, snow, washboard roads, rocks, whatever seems to need less tire pressure. Don't travel much above 25 - 30 mph aired down, and usually just crawl around at 5 mph or less. Haven't lost a bead, yet.

What'cha all do for airing down?
 

JMT

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10-12 psi. Haven't lost a bead. I've driven up to 55 mph for 30 miles on highway and around town for a week in Moab while I was there. Made life a lot easier. Had no problems.
 
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StG58

StG58

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Sure makes a difference when traction gets sketchy.

10-12 psi. Haven't lost a bead. I've driven up to 55 mph for 30 miles on highway and around town for a week in Moab while I was there. Made life a lot easier. Had no problems.
Interesting that you've been up to 55 mph aired down. What's the inside of your tires look like? I trashed the lining on a set of tires running the pressure too low one time. But those were street tires, and I wasn't going 55. Our off road tires must be made of sterner stuff.
 

pagrey

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12psi for easy stuff just to smooth it out. 8psi if it's a bit tough or slow going. I've dropped to 5psi with BFG KMs but have lost a bead at that pressure, they were pretty soft tires. 31s on 8" wide wheels. Big change once you get to single digits but it depends on the tire.

I've run faster than 55 at 12psi for extended periods in the dirt, it wasn't an issue for me. 12psi doesn't seem all that low once you've gone to single digits.
 
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derekmac

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For my 35x12.5x15's I generally run 10psi off-road. Wintertime, depending on the snow depth it'll be 5-10psi.
 
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StG58

StG58

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Good point. Dropping from, say, 28 to 20 psi doesn't seem to give you much, but when you get down to 9 - 10 psi a pound or two difference makes a difference it seems.
 

tworley

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8psi on rough trails.

I was worried about popping beads that I used to do 12. Over time Ive just naturally gone lower. So far multiple runs at 8 psi on a 15x8 wheel has been successful .
 
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StG58

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Anecdotally, and from my own experience, it seems that a set of tires needs to be broken in as well. They start to really work better once you run them aired down on rough terrain a couple of times. Anyone else notice this?
 

IPerkWVU

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I'm usually around 11-12 off road, 26 on the street with load E tires, always been cautious about going lower, though im sure it would help a bit. At 12 it's a big difference from 25 and sometimes (at least in Tennessee) there's often a bit of blacktop and 40 mph travel between trail systems. A lot of moderate jku folks I wheel with won't go below 15
 

jjvw

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Anecdotally, and from my own experience, it seems that a set of tires needs to be broken in as well. They start to really work better once you run them aired down on rough terrain a couple of times. Anyone else notice this?
On my load range E 33s, I certainly noticed this. They are far less stiff now halfway through their life than when new.

8psi has been my go to for a long time. Never blown a bead except for the one time that it was entirely my fault. That was a much higher psi.
 
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psrivats

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The lowest I have gone is 15psi and it made a world of difference on some rougher FS roads. Would like to not chicken out and try 10-12 psi in the future.
 
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jodomcfrodo

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I think it also depends on how nice / quality / not Chinese your wheels are. My Thaitanium wheels aren’t great. 35” tire, 15x8 wheel at 12 PSI and I could hear air burping out on multiple occasions on the way down Holy Cross.
 

whitrzac

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31x10.5 on 15x8 wheels.

I've popped a bead 3 different times at ~12-14psi. Ruts are not friendly to tires...
 

jjvw

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Years ago, I recall a discussion about determining the optimal air down pressure. It involved airing down until the center of the tire patch would lift off the ground. That was the point past where the tire contact patch was at it's maximum.

I think this required repeatedly stamping the increasingly aired down tire with a floor jack and cardboard.
 
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pagrey

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Years ago, I recall a discussion about determining the optimal air down pressure. It involved airing down until the center of the tire patch would lift off the ground. That was the point past where the tire contact patch was at it's maximuimun.
I read somewhere to put something an inch away from the tire and air down until the tire reaches it. Now I just eyeball it and use the gauge to make sure I'm not running at 4psi.

Edit: really helps when you are wheeling with people that haven't gone before and have different tires and wheels