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Old 09-08-2009, 07:44 PM   #21
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Re: Question, Airing Down for off road?????

My 285/75/16 E's are rated to run at 80. Typically I lower to 35 on wash board and keep the speed no faster than 30MPH. Running 40 to 45 helps less but I can travel faster. Just depends on the terrain. Don't have a clue if it's correct but I won't run high speeds at a lower PSI because of tire stress.
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Old 09-09-2009, 04:52 AM   #22
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Re: Question, Airing Down for off road?????

In my opinion, the good pressure is when the tyre is resting flat on the whole width.

One visual way to reach that pressure under load is to mark a line with chalk across the tire and drive in strait line for a short distance. Check the line.
If evenly worn than you correct.
If worn in center than you are over pressure.
If worn on the sides your under pressure,, might be hard to see this case.

My 2 cents:
On the LC I used the following:
Street : 2.3 to 2.5 Bar
Medium off road : 1.8 to 2.0 Bar
Soft sand : 1.0 to 1.5 Bar
Edit: pure information of reduction ratio... The LC is definitelly lighter than the SMB...
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Old 09-09-2009, 06:13 AM   #23
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Re: Question, Airing Down for off road?????

But Andrew how heavy is your LC?
The Van are to my knowledge much heavier and have greater load capacity for the 250(2500) and 350(3500) models...
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Old 09-09-2009, 09:13 AM   #24
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Re: Question, Airing Down for off road?????

So I admit to being a bit naive when it comes to serious "off roading" and don't air down my tires, but just drive slower. I've got 35k on my 2005 SMB, and have only "needed" to engage the front axle for about 100 miles of that. A typical trip for me would be 300 miles of paved road, 30 miles of forest service road (shared with Suburus and Vanagons), and then 3 miles of bumpety bump to the lake. I guess I would be concerend that the 30 miles of forest service road with aired down tires would be as harmful as highway driving with aired down tires.

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Old 09-09-2009, 10:48 AM   #25
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Re: Question, Airing Down for off road?????

As long as you're not getting stuck... and once you are, it's not going to be fun to get out and air down.

I've had the Jeep out in deep snow with Mud TAs (the wrong thing for deep snow) and aired down to 10psi I drove circles around Jeeps of all sizes with full pressure... had to, because I spent all day pulling them out repeatedly.

I would rather air down (air on the side of caution.. ba-dump-dump ) but in the van I tend not to because I don't have OBA, which leaves me either driving at full pressure, letting a few PSI out but not really airing down, or airing down and then limping 50+ miles on pavement (driving slow < 30mph)

Unfortunatly the OBA project is expensive and keeps getting delayed, although I really do prefer to air waaay down.
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Old 09-09-2009, 12:55 PM   #26
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Re: Question, Airing Down for off road?????

Thanks Jage, I have to admit, I've taken my old Trooper places that I won't take The Van. Maybe it's because I'm older (or just don't feel the need to be way hell and gone off the road). I could probably get to the places I go to now with a good pickup with a locking rear diff, but I like the comfort of The Van, and the ability to have "it all in one".
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Old 09-09-2009, 03:04 PM   #27
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Re: Question, Airing Down for off road?????

Quote:
Originally Posted by saabman
But Andrew how heavy is your LC?...
Saabman, corrected my data; the visual test can be done with any tyre and weight
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Old 09-23-2009, 01:39 PM   #28
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Re: Question, Airing Down for off road?????

We have the 315 D load rated BFG All terrain tires from SMB and I usually lower them to 40 psi when hot which is about 35 psi cold. On the street I run at full pressure which is 50 psi. This takes the bite our of the washboard and also keeps the rear wheels from hoping on tight uphill corners. At this pressure I keep my speed under 40mph so I don't overheat the tires.

On our last trip we did some 4-wheeling around the shore of Lake Powell and after burring one back wheel up to the axle and having to winch ourselves out, we lowered the tire pressure to 25 psi. At this pressure I would recommend keeping your speed really low 15mph or under and being very careful of sidewall damage by sharp rocks.



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Old 10-08-2009, 05:08 PM   #29
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Re: Question, Airing Down for off road?????

While running 25# on washboard in Death Valley last spring I pinched both pass. side/ sidewalls on my 285/70/17s on a big rock. Had I been at my usual 55# I probably would have avoided cutting the side walls on the rim. It was my fault for not being vigilent and I was only going about 15mph. A new 285/70/17 costs $400 in Lone Pine! If you air down....you have to bewair!!! sorry..
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