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Airing down discussion


wildbill

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15x8 (non beadlock) with 35s, I'm usually around 10-12 aired down. Haven't done single digits yet, but not sure I've had a need at this point
 

Plumber1

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I typically run mine at 8 sometimes 10 psi. The biggest beginner mistake is being afraid to air down enough. If you're not below 15 psi you're not really aired down.

Look at the footprint size difference here. Bigger footprint = increased traction.

View attachment 116174
Now did you actually make this poster ? if so it very well shows the difference
 

Flivver250

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I wheel in the desert. Been as low as 5 lbs, usually keep it at about 8 lbs. 33 x 12.5 x 15. Haven't popped a bead yet.
 

Plumber1

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I did pop a bead on my YJ running 33's aired down to about 11 PSI. We had to change the tire and mount the spare several years ago. About 2 hours later on the trail a nice jeeper came by and what happen to your spare tire. I went on to explain that we popped the bead, when he said if I wanted he could reset it and inflate it back up. I asked how then he went on to show me his York OBA and he did inflate the tire. That when I said holly shit I gotta have one of those. Got back home and found the Kilby OBA site and the rest is history.
 
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JMT

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Sure makes a difference when traction gets sketchy.


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.
They look fine. I only did it for 6 or 7 days. I would never have done it except a group I wheeled with the first day did it, so I asked. They had been wheelin’ Moab for 14 years so I assumed if it was good enough for them it would work for me. The tires are Cooper STT Pro and have worn pretty evenly. I’ve got 21,000 miles on these. I’m thinking I’ll be up for a new set in another 9,000 miles. Good topic.

P.s. I’m much closer to your neck of the woods now. Maybe I’ll see some of those tight trails your nimble 4 angry squirrels sees soon!
 
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StG58

StG58

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It would be cool if somebody could post up pics of a decent sized tire wrapping around an obstacle when aired down vs the same tire at street pressure on the same obstacle.
 
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Goatman

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I remember an article in JP mag about this and they were using ink on cardboard. They came up with some "optimum" pressure around 15 psi IIRC. their "science" was with one Jeep on one tire type. I find it hard to believe there is only one ideal offroad pressure. I had a CJ-5 on 35's some 30 years ago and know for a fact they wouldn't bulge a bit at 15 psi. Ran them around 7-8. Have yet to really work my TJ offroad much yet, but the Coopers on my old Nissan PU were happy around 12 psi.
 

jjvw

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I remember an article in JP mag about this and they were using ink on cardboard. They came up with some "optimum" pressure around 15 psi IIRC. their "science" was with one Jeep on one tire type. I find it hard to believe there is only one ideal offroad pressure. I had a CJ-5 on 35's some 30 years ago and know for a fact they wouldn't bulge a bit at 15 psi. Ran them around 7-8. Have yet to really work my TJ offroad much yet, but the Coopers on my old Nissan PU were happy around 12 psi.
That's where the process I describe earlier comes into play, at least as far as maximizing the contact patch for the specific vehicle/tire combination is concerned. Whether or not there are optimal pressures for different scenarios is a whole other discussion.
 
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pagrey

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For me the biggest misunderstanding was air down for traction only. Early on I never really had traction issues so there wasn't much motivation to air down. Nobody really told me clearly that airing down keeps the ride smooth and makes things massively better for just about every nut and bolt on the Jeep. If they did tell me I didn't listen. The wear and tear of running even on graded dirt roads at street pressures is so much worse. I often hear people say "you don't even need to air down" and think about that.
 
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tworley

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It would be cool if somebody could post up pics of a decent sized tire wrapping around an obstacle when aired down vs the same tire at street pressure on the same obstacle.
Dont have a street pressure but here are 33s at 8 psi
IMG_1432.JPG

IMG_1426.JPG


Here are my 35s at 8psi just sitting. The rear is forming nicely
20190831_130410.jpg
 

mgroeger

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Dang... does everyone have 35s except for like 4 of us? ;)

Well I am still learning, been dropping my 10.5 x 33s down to 15-18 but clearly I need to be 15 or lower. Will be trying it out next time on the trails.
 
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