Well, after spotting a couple of XK's over obstacles one guy had a bunch of trouble making it and I was confused at to what the problem was. Then it hit me he said earlier he didn't air down what a difference it makes uh. During the first day we headed down some long rocky service roads. About an hour into it I got fed up and air downed to 25PSI and instantly my ride smoothed right out and the family was happy again and the wife just wanted to know why I didn't do it an hour ago.
1.5 barrs = 21.7 lbs/in^2
1 barr = 14.5 lbs/in^2
Arrie is our friend in South Africa, so I guess they use barr as their unit of pressure over there. Actually, I wonder why they don't use kilopascals, but it's just a factor of 10.
2007 Commander Overland / 4" SuperLift / 285/70R17 Cooper Discoverer ST Maxx / Rusty's adjustable rear UCAs / Carolina Driveline front drive shaft / Flashpaq / DRLs & Tilting Mirrors / Autolite Iridiums / Cobra 29LX Chrome LE CB & Firestik antenna / Rear fog lights / Mopar Grille Guard with HID driving lights
"4 wheel drive does not mean 4 wheel stop!" -Lee Goldberg, WABC TV weatherman
I air down to lower than 15 psi when driving on soft dry sand ,, I also put it on around 10 psi when going to extreme soft sand and tough areas, and even with such pressure we sometimes get stuck
Second Jeep Commander ,,,, Current
2007 XH (International model), Green Metallic, Limited, 5.7L HEMI, Quadra-Drive II
Spidertax 1.5" wheel spacer, Flowmaster 50 SUV muffler, Sylvaniya Ultra bulbs for high beam and fog lights, K&N replacement filter
First Jeep Commander,,,, Gone
2007 XH (International model), Light Graystone Pearl, Sport (Base model) , 4.7L Quadra-Trac II.
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Don't you risk breaking the bead at such low pressures...?
2007 Commander Overland / 4" SuperLift / 285/70R17 Cooper Discoverer ST Maxx / Rusty's adjustable rear UCAs / Carolina Driveline front drive shaft / Flashpaq / DRLs & Tilting Mirrors / Autolite Iridiums / Cobra 29LX Chrome LE CB & Firestik antenna / Rear fog lights / Mopar Grille Guard with HID driving lights
"4 wheel drive does not mean 4 wheel stop!" -Lee Goldberg, WABC TV weatherman
no your still good down to 15PSI but I wouldn't go much lower then that with out bead locks IMOOriginally Posted by lekmedm
I have never popped a bead and I always air down that low.
2007 4.7 Liter XK | Front Modified OME HD Lift | Rear 4" Superlift | JBA UCA's | Rusty's Rear Adjustable Track Bar | Rysty’s Adjustable Upper and Lower Rear Control Arms w/Heim Joints | Mickey Thompson Classic III 17x9 Wheels | 315/70R17 Goodyear Duratracs | Airflow Snorkel | Flowmaster 40 Series Muffler | Superchips Flashpaq | Mopar Skids | 4xGuard Belly Guard | American Rebel Rear Diff Cover | Rear Powertrax No-Slip | Front Electronic Locker | Rear Heat/AC Delete
In Western Australia you do a lot of beach work and also sharp, rocky terrain in the north. We air down for both, rocks approx 25psi. With sand it is a bit dependent on the make and style of tyre you are running, they have different deflation characteristics.
With sand you are trying to lenghen the tread footprint, with one of your tyres at normal pressure slide a ruler under the front and rear at a right angles then mark on the pavement the contact lengh. Now reduce the pressure and do the same again, you will soon see once you get under 18psi you get huge improvement in footprint. We normally drop to 20psi then if you get in trouble you can still drop further to get out. 12psi is the lowest I would go to without beadlocks and you would pump up as soon as you hit firm ground because a lot of sidewall is on the ground.
So what do you air down to? 15? or lower? Sal's post suggested not going below 15. I have run on flat tires without
popping a bead but it shouldnt be done....
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