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chrishaynesusa

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Posts: 26
 #1 
I run an Xterra setup for rock crawling and camping.
GVW of 6320 lbs with gear and I run 16 PSI on Goodyear MT's with kevlar sidewalls
works great all day long.
encore889

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Posts: 29
 #2 
Exactly greyscreek... i dont get how trucks and suvs got so damn heavy and so huge...i used to hv a lil Mitsubishi mighty max 2wd and i would go anywhere and everywhere and over anything in that lil rig. And get good mileage to boot... now all i see is ginormous 2 ton trucks w campers on top... worrying about getting around boulders.... lo
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GreysCreek

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Posts: 6
 #3 
Back in the early 60's we used to drive our little Datsun station wagon into Saline. Would run tires over the ruts. We brought several large trucks to our ranch(not 4x4's, but just my Dad's big old paint trucks to haul stuff in and out. The roads were pretty rough at times and impassable once in a while, but usually we made it through okay. Always loved looking for the burro ears amongst the rocks.
Sam D.

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Posts: 689
 #4 
In my experience airing down street rated tires by more than 3-5 psi exposes sidewalls and makes the tires looked like chewed on the inside further reducing the lifespan.
VegasNaturist

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Posts: 39
 #5 
A lot has to do with the type of tire you're running. Mentioned above was "Truck Rated" tires. These are typically "LT" or light truck tires and have an "E" rating, but are in fact still street tires. They are designed to handle a load, but not rough terrain. Although these have relatively stiff sidewalls to carry loads, the sidewalls are vulnerable. When running these tires, you are limited as to how much you can air down. Hence the above recommendation to 24 - 26 PSI. And even that may be too low depending on conditions. Then there are "All Terrain", "Mud Terrain" and other designations for tires that are more geared towards off road applications. In my old Jeep (recently totalled, RIP my friend), I was running Toyo Open Country AT II Extremes and I could easily air down to 12 - 15 PSI. These tires are rated as "LT" tires, 10 ply and 8 ply sidewalls, but they are designed for off road use and have tread lugs half way down the sidewalls. My new Jeep came with BFG Mud-Terrain KM2's and 17 PSI seems to be the sweet spot for these. Generally speaking, with street rated tires, air down till the tires JUST start to squat and stop there, then take it slow and easy. With off road tires, you'll just have to experiment to find the ideal PSI and go for it. NO, I'm not advocating speeding down the trails, but one would be less vulnerable.

John
bobhuckaby

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Posts: 132
 #6 
I remind myself that "easy does it does less damage"
the experience since I opened this thread has confirmed that 24psi works pretty well on loaded Dodge 2500
I am glad to have E tires with 10ply sidewall as the sidewalls are showing rock scrapes
Bob from Tahoe
SoCalSteve

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Posts: 23
 #7 
Slowing down helps. Can't miss much going fast. Slow down and enjoy the ride.
starryeyedwonder

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Posts: 8
 #8 
Was in the springs last week (Nov 2016) and saw two vehicles with punctures.  One was an obviously overloaded pickup truck with street tires and the other was a heavily loaded 4x4 with new All-Terrain KO2 tires that got a sidewall puncture.

Seeing those two punctures led to a long discussion in the tub with a highly-seasoned off-roader. His comment was that "you have to search for the sweet spot. It's a triangulation between speed, weight and road conditions. Not enough air-down and it's hard on the suspension components. Too much air-down and you expose the sidewall to punctures."

I pressed him for numbers.  If you're running a 5,000 pound vehicle with truck-rated tires and limiting your speed to 25 - 30 mph on washboard, then 24 - 26 psi cold. I asked if you would ever air down to 15 - 18 psi.  He said, "Only if you're in deep snow."  I imagine deep sand, as well.
bobhuckaby

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Posts: 132
 #9 
thanks for the feedback
went in for president's via north pass, met SilverBob at the turnoff and got his viewpoint actually looking at my tires and rig, he suggested 24
my tires run at 65 highway, so I thought to go 40, but used the input to go to 30, worked out awesome feeling like 70% of the washboard was absorbed going in, no issues in steering control in the pass
on the way out up the grade I wished I had gone lower but left it so I could wait for Big Pine to refill. corners felt a little squishy on the pavement, btw the Shell station has air hose in back that is much nicer than waiting for the portable compressor to put in that much air
Bob from Tahoe
trigger

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Posts: 176
 #10 
How low to go varies a lot. Depends on the individual weight of your vehicle, the aftermarket items you put on and the load your carrying (beer,whiskey,tequila etc.). Basically depends on your total weight at the time your airing down. What type of tires you have and the wheel size makes a difference too. Larger the wheel the less sidewall and you should not air down as much. Some offroad tires have large sidewall lugs that act as an additional tread (protects the sidewall more) when you air way down so you can get away with going lower than others. It would be helpful to know exactly what tire your running and the apprx weight of your rig. My rig is apprx 8500 lbs with typically an additional 1000 lbs in gear for a total of 9500 lbs. I have 35" toyo mud terrains on 17 inch wheels. My fronts, while offroad, are aired down to 22 PSI and typically I'm carrying the same cargo weight in the bed each trip so I run the rears at 26 PSI when loaded. When the rear is unloaded I run the rear tires at 16 PSI. I leave the fronts at 22. At this point the rear of my truck is lighter therefore less PSI in the rear tires. The biggest mistake people make in my experience is not airing down enough. Go low! Your truck and your body will thank you.
Commando Paul

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Posts: 81
 #11 
I have BFG ATs on a GMC 1500, 265/75 R 16s.  Run them at 35 cold on hiway, and when I stop to air down they are at 40.  Let down to 28, and after cooling in camp, they are at 25. Works out to about a 30% air-down, which is good for washboard/rocky cobble.  If I was rock crawling in the Toyota, I might go down 40%.

Airing down reduces the chance of punctures both tread and sidewall, unless you are really hauling ass.
Sam D.

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Posts: 689
 #12 
Original discussion is here:

http://forum.salinepreservation.org/post/airing-down-4639349?highlight=airing+down
SunMan

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Posts: 44
 #13 

It definitely works. I'd start with removing 10lbs and go from there. You may be able to go lower, with a bigger truck you are likely running with higher pressure.

bobhuckaby

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Posts: 132
 #14 
The washboard on the county road has gotten pretty severe, even in the valley now, so I am wondering about airing down to cushion the ride and keep my teeth intact.  I have a heavy truck running good tires with E load 10-ply sidewalls, but I am scared about exposure to sidewall punctures (and I hate changing tires on the truck, even though I have 2 full-size spares and a floor jack).
I remember some discussions in the past but I can't find them, so putting it out there again.
Risks?  How low to go?  Affect on the pass snow/ice?  Speed?  Other advice?
Thanks.
Bob from Tahoe
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