Author Topic: Airing down  (Read 3378 times)

Offline Doc

  • 2002 Jeep TJ
  • Administrator, Webmaster, Treasurer
  • Club Founder
  • **
  • Posts: 9939
  • Total likes: 263
  • Karma: 144
  • It's a Jeep thing... And it's WICKED expensive!
  • Model and Year: 99 Cherokee XJ Clasic, 99 Cherokee Sport, 99 TJ X, 02 TJ X, CJ7 and now another 2002 TJ X
Re: Airing down
« Reply #23 on: March 17, 2016, 05:58:16 PM »
I guess I have had lots of luck, I always air down to 12-15 only lost a bead once and seem to get great traction
are you talking about that time we did stonehouse and we used a high lift pressed against my rig and into your tire to pull the chunk of wood out of the bead so it would hold air?
or was there another time? lol!

Sent from my SAMSUNG-SM-T337A using Tapatalk

lol .. NOPE .. that was it .. I think there are photos here somewhere  LOL
Enjoy the trails ... Tread Lightly, Respect the Landowner ... and Get Permission!

Offline Lucifer

  • Dreaming of double-digit mpg...
  • Non Supporting Members
  • Posts: 5315
  • Total likes: 151
  • Karma: 3
  • Wishing I had TJKDave's Crawl Ratio...
  • Model and Year: 2002 TJ Sport
Re: Airing down
« Reply #22 on: March 15, 2016, 08:15:13 PM »
I guess I have had lots of luck, I always air down to 12-15 only lost a bead once and seem to get great traction
are you talking about that time we did stonehouse and we used a high lift pressed against my rig and into your tire to pull the chunk of wood out of the bead so it would hold air?
or was there another time? lol!

Sent from my SAMSUNG-SM-T337A using Tapatalk

Don't know what that sound is?  Keep driving. She'll let you know in a minute if it's going to be an issue...

Offline Doc

  • 2002 Jeep TJ
  • Administrator, Webmaster, Treasurer
  • Club Founder
  • **
  • Posts: 9939
  • Total likes: 263
  • Karma: 144
  • It's a Jeep thing... And it's WICKED expensive!
  • Model and Year: 99 Cherokee XJ Clasic, 99 Cherokee Sport, 99 TJ X, 02 TJ X, CJ7 and now another 2002 TJ X
Re: Airing down
« Reply #21 on: March 15, 2016, 08:07:58 PM »
I guess I have had lots of luck, I always air down to 12-15 only lost a bead once and seem to get great traction
Enjoy the trails ... Tread Lightly, Respect the Landowner ... and Get Permission!

Offline djljeep

Re: Airing down
« Reply #20 on: March 15, 2016, 07:54:55 PM »

More to wolfmoons point, I've found that much lower than 8 or 10 on my tires and the tire begins to dent too much when rolling. Instead of going up and over a log, it will collapse around the log and you begin to push the rim against it.
There's a sweet spot - I've found it to typically be between 15 and 8 psi across the board.

Definitely a sweet spot but its different for every tire.  If I ran my bias swampers much higher than 9-10 I bounce off of everything, but at 6-7 it'll crawl pretty good.

It takes a super low pressure to cause Rim/tire interaction, again different for every tire, but like 3-4 psi in most normal wheeling - the website for Stauns talks about this because you have to figure it out to see how low you can get away with.  To me the sweet spot is getting as much deformation as possible out of the tire without causing damage, because you get crazy traction - obviously this only works when using a super low gear, beefy drivetrain, or with an internal type beadlock like a Staun.

A bunch of WMMJ folks are running stauns and can run reliably in the 3-5 psi range, and you would not believe what a TSL or bogger will do at that kind of pressure.  It's like friggin suction cups.

Offline Lucifer

  • Dreaming of double-digit mpg...
  • Non Supporting Members
  • Posts: 5315
  • Total likes: 151
  • Karma: 3
  • Wishing I had TJKDave's Crawl Ratio...
  • Model and Year: 2002 TJ Sport
Re: Airing down
« Reply #19 on: March 15, 2016, 07:51:39 AM »
I usually run my 36 TSLs in upper single digits.
I lost a bead once in the 4 or 5 years I've wheeled that low.
.. and it was due to snapping the valve stem off.
More to wolfmoons point, I've found that much lower than 8 or 10 on my tires and the tire begins to dent too much when rolling. Instead of going up and over a log, it will collapse around the log and you begin to push the rim against it.
There's a sweet spot - I've found it to typically be between 15 and 8 psi across the board.
Don't know what that sound is?  Keep driving. She'll let you know in a minute if it's going to be an issue...

Offline woolyworm

  • Cheat J 101...Build a Jeep
  • Non Supporting Member
  • Posts: 3163
  • Total likes: 622
  • Karma: 22
  • 75 CJ7
Re: Airing down
« Reply #18 on: March 10, 2016, 06:16:39 PM »
The Irok ND sidewalls are super flexy.  I get really good flex at 10-12 and imagine lower would be even better.


Wooly
75CJ7, 72 AMC 304, T18, 45:1 crawl, chromo axles, warn hubs, 3" Black Diamond, 1/4" belly skid, front locker, other goodies, sweat ...

Offline TJKDave

  • 2019 Supporting Members
  • *
  • Posts: 3830
  • Total likes: 480
  • Karma: 38
  • Crawl Ratio: TJ 47.50:1 JK 58.9:1
  • Model and Year: 1999 TJ, 2012 JK TreadLightly Supporter
Re: Airing down
« Reply #17 on: March 10, 2016, 08:20:45 AM »
Every tire/driver has their own sweet spot for tire pressure.   I've found that my Rockers do best in the 6psi range.   Haven't lost a bead at that pressure yet.   
I've not found that magical number yet for the Trail Grapplers.  They're pretty good at 12psi, but I need to wheel them lower to find out.
99% of your JK questions answered here thanks to  JLC08JK on JeepForum for this information:

http://www.jeepforum.com/forum/f96/jeep-jk-frequently-asked-questions-will-rub-links-popular-threads-1074059/

Offline yamaha225

  • 2019 Supporting Members
  • *
  • Posts: 813
  • Total likes: 354
  • Karma: 11
  • Jeepin on a college budget
    • Maineiac Offroad
  • Model and Year: 1997 Jeep Wrangler
Re: Airing down
« Reply #16 on: March 10, 2016, 07:18:04 AM »
I was flabbergasted the first time I aired down at how much better the traction was. Not to mention the ride quality improves sevenfold. I've gone pretty low (7-8 psi) on 31's and haven't had any issues (knock on wood) with a bead coming off.
'97 TJ, 4 really angry squirrels under the hood, AX-5, 31 MT/R-K's, 44:1 crawl ratio, 8000 Smittybilt X2O winch, Sanden OBA, 2.5 inch RC spring lift, Custom Fab Rear bumper, Ford 8.8 Rear Axle with 4.10's and Trac Lok Limit Slip, Dana 30 Front Axle with 4.10's and a Aussie Locker, Metalcloak Rear Upper Control Arms and Trackbar

Offline rockman

  • 2019 Supporting Members
  • *
  • Posts: 633
  • Total likes: 284
  • Karma: 16
  • Model and Year: 97 TJ and 03 Rubicon
Re: Airing down
« Reply #15 on: March 08, 2016, 07:39:01 PM »
The best mod for off-roading is properly airing down and it's free. It's common for guys to not want to go into the single digits but the traction is incredible. It's not just the size of the tire pattern but the ability of the casing to contour to the ground, especially with radials. It's my belief that the casing gives me as much or more traction than the tread. When you spin a radial you're giving up it's best advantage.

Offline NoisyCricket

  • 2019 Supporting Members
  • *
  • Posts: 315
  • Total likes: 114
  • Karma: 3
  • Jeep Brakes are only a concept.
  • Model and Year: 1975 CJ5
Re: Airing down
« Reply #14 on: March 08, 2016, 09:08:14 AM »
I always get a chuckle at Jeep Jamboree when the participants realize I air up to what they are airing down to at ~15-20 psi.

 LOL  I'll bet you get a lot of funny looks.

Offline djljeep

Re: Airing down
« Reply #13 on: March 07, 2016, 10:43:20 PM »
I always get a chuckle at Jeep Jamboree when the participants realize I air up to what they are airing down to at ~15-20 psi.

Offline Grumpy

  • 2019 Supporting Members
  • *
  • Posts: 498
  • Total likes: 88
  • Karma: 2
    • Facebook
  • Model and Year: Wrangler 2004
Re: Airing down
« Reply #12 on: March 07, 2016, 09:52:49 PM »
That fine grimm, unless you need to drive 50 or so to get home after a ride.
It ain't Easy being Easy!

Offline woolyworm

  • Cheat J 101...Build a Jeep
  • Non Supporting Member
  • Posts: 3163
  • Total likes: 622
  • Karma: 22
  • 75 CJ7
Re: Airing down
« Reply #11 on: March 06, 2016, 02:12:44 PM »
Cool graphic.  This is with about 1000 lbs on the tire at different psi.  In March 2016 JP mag.


Wooly
75CJ7, 72 AMC 304, T18, 45:1 crawl, chromo axles, warn hubs, 3" Black Diamond, 1/4" belly skid, front locker, other goodies, sweat ...

Offline Grimm

  • Self taught Trained Professional
  • 2019 Supporting Members
  • *
  • Posts: 2185
  • Total likes: 117
  • Karma: 32
  • Too. Many. Projects.
  • Model and Year: Wouldn't you like to know
Re: Airing down
« Reply #10 on: February 02, 2015, 09:06:05 PM »
I usually air down to around 15 psi for the summer ... still has good street manners and still very capable off road. I air down once for the first ride I go on in the spring and don't usually air back up until after the chili crawl
What could POSSIBLY go wrong?

Offline 06Rubi

Re: Airing down
« Reply #9 on: January 31, 2015, 09:13:12 AM »
I run 8 usually without beadlocks and on steelies.  Have been for years.  I've yet to roll a tire.
01 XJ, 33" TSL's, custom bumpers, XRC8, Lockrite/Aussie, MonkeyBars sliders, 5100's, etc

Offline djljeep

Re: Airing down
« Reply #8 on: January 30, 2015, 12:24:17 AM »
Of late I've been running ~6 without bead locks in Dad's TJ.  Previously 36X12.5R15 on a 10" rim now on 8" because I was getting to many bead leaks from trees and stuff.  I think I ran all of Jamboree including pre-running stonewall and sherwoods at 5-6 in my CJ5 without an issue.  Hell last month I ran 2 with no success, so I went lower, which went about as well as you could expect.    The other WMMJ guys with Stauns can run as low as 1 or 2 all day.  You haven't seen a bogger dig until you've seen one that low.

Offline yamaha225

  • 2019 Supporting Members
  • *
  • Posts: 813
  • Total likes: 354
  • Karma: 11
  • Jeepin on a college budget
    • Maineiac Offroad
  • Model and Year: 1997 Jeep Wrangler
Re: Airing down
« Reply #7 on: January 26, 2015, 10:47:13 PM »
https://www.youtube.com/watch?v=qRMucnHURjI

This is a neat video on the subject. Love this stuff
'97 TJ, 4 really angry squirrels under the hood, AX-5, 31 MT/R-K's, 44:1 crawl ratio, 8000 Smittybilt X2O winch, Sanden OBA, 2.5 inch RC spring lift, Custom Fab Rear bumper, Ford 8.8 Rear Axle with 4.10's and Trac Lok Limit Slip, Dana 30 Front Axle with 4.10's and a Aussie Locker, Metalcloak Rear Upper Control Arms and Trackbar

Offline Mike Reynolds

  • President
  • **
  • Posts: 6858
  • Total likes: 958
  • Karma: 27
  • Model and Year: 2005 Wrangler Willys Edition
Re: Airing down
« Reply #6 on: January 26, 2015, 09:52:35 PM »
single digits is sketchy but I'll drop to 7 if trail conditions call for it
Jeepin ain't easy

Offline yamaha225

  • 2019 Supporting Members
  • *
  • Posts: 813
  • Total likes: 354
  • Karma: 11
  • Jeepin on a college budget
    • Maineiac Offroad
  • Model and Year: 1997 Jeep Wrangler
Re: Airing down
« Reply #5 on: January 26, 2015, 09:09:12 PM »
I've run 10 now quite a few times and it seems to work really well. At the trail day at my house Rockman ran 7 and said he does every time and has only popped a bead once. And yes Paul I think it takes some experimentation and conditions can change in an instant on the trail. I loved that discussion. Really interesting stuff to me!
'97 TJ, 4 really angry squirrels under the hood, AX-5, 31 MT/R-K's, 44:1 crawl ratio, 8000 Smittybilt X2O winch, Sanden OBA, 2.5 inch RC spring lift, Custom Fab Rear bumper, Ford 8.8 Rear Axle with 4.10's and Trac Lok Limit Slip, Dana 30 Front Axle with 4.10's and a Aussie Locker, Metalcloak Rear Upper Control Arms and Trackbar

Offline woolyworm

  • Cheat J 101...Build a Jeep
  • Non Supporting Member
  • Posts: 3163
  • Total likes: 622
  • Karma: 22
  • 75 CJ7
Re: Airing down
« Reply #4 on: January 26, 2015, 08:15:05 PM »
Id say 8 is about the limit without BLs and you'll likely PPP one off here and there at that pressure.  And.....contrary to popular belief and at the risk of staring another tire pressure debate, you can have too much contact patch from lowering pressure.  Depends on vehicle weight and ground material and tread pattern and probably 57.5 other variables.

Anyway, yes 8 is doable but you'll probably lose a bead here and there.


Wooly
75CJ7, 72 AMC 304, T18, 45:1 crawl, chromo axles, warn hubs, 3" Black Diamond, 1/4" belly skid, front locker, other goodies, sweat ...

74Cj5

  • Guest
Re: Airing down
« Reply #3 on: January 26, 2015, 07:38:49 PM »
Pretty cool picture showing the footprint of an aired down tire versus street pressure
Could you run 8 psi without bead-locks?  Roll the tire off the bead in the woods rocks logs stumps etc?

Offline woolyworm

  • Cheat J 101...Build a Jeep
  • Non Supporting Member
  • Posts: 3163
  • Total likes: 622
  • Karma: 22
  • 75 CJ7
Re: Airing down
« Reply #2 on: January 26, 2015, 06:22:28 PM »
Neat


Wooly
75CJ7, 72 AMC 304, T18, 45:1 crawl, chromo axles, warn hubs, 3" Black Diamond, 1/4" belly skid, front locker, other goodies, sweat ...

Offline yamaha225

  • 2019 Supporting Members
  • *
  • Posts: 813
  • Total likes: 354
  • Karma: 11
  • Jeepin on a college budget
    • Maineiac Offroad
  • Model and Year: 1997 Jeep Wrangler
Airing down
« Reply #1 on: January 26, 2015, 04:22:20 PM »
Pretty cool picture showing the footprint of an aired down tire versus street pressure

[attachment deleted by admin]
'97 TJ, 4 really angry squirrels under the hood, AX-5, 31 MT/R-K's, 44:1 crawl ratio, 8000 Smittybilt X2O winch, Sanden OBA, 2.5 inch RC spring lift, Custom Fab Rear bumper, Ford 8.8 Rear Axle with 4.10's and Trac Lok Limit Slip, Dana 30 Front Axle with 4.10's and a Aussie Locker, Metalcloak Rear Upper Control Arms and Trackbar