How low would you go......regarding tire pressure that is?

If you want to get max benefits for load carrying, pump them to the max. psi as stated on the door jam. for original equipment tires.

But, you can always weigh your loaded trip ready truck and then consult the spec sheet for your tires and air accordingly.

remember when you air down tires on a dually you don't want to go so low that the rear tires kiss each other. Never having aired mine done for traveling on sand or snow I don't know where that would be. I have aired tires down on srw trucks but never when I had a max load on them.And I do it with my jeep but even then I air back up before traveling at road speeds.

EG,
You are not going to get much response on this as very few dualie owners air down their tires at all. I don't currently own a dualie, but have some experience with airing them down. The myth is that it's a no-no to let the tire's sidewalls touch while rolling down the beach. The truth is you don't want them to touch and get hot through abrassion. If you go slowly enough to get no heat build up and not too far at a time, you can take the pressure down to say 30 pounds without undue damage to the tires and still have enough floatation to make it work. The woe is actually lowering the pressure on six tires, two of which are hidden and hard to get to. I've done this and really don't think it's worth it, it's just so far to go for a few hundred feet of sand. But if are going to say, Pismo Beach for a week, or the Yuma Dunes you don't have to move much so it will be worth it.
jefe

My fronts run at 80psi and each tire in the rear run at 65psi (door jam recommended tire pressures) during highway driving.

My F350 tyre pressures are dictated by the load on the wheels, not by what is on a sticker.

Like the OP I drop the pressures when I'm likely to be on poor roads for a long distance, especially corrugations. Even a few psi out of the front tyres can make a huge difference to the ride on bad corrugations. Rule of thumb is drop to 80% and maximum speed drops to 80% as well (in practice this means 50mph). If I go lower then maximum speed goes lower as well. Duallies complicate things considerably, especially if I want to lower the pressures for a long distance, but I would be happy to air them down a bit as long as they weren't actually rubbing. Sand driving is different and then it is a matter of going as low as is necessary, or stay out of the sand.

On my OKA which has single tyres front and back, I have run them at 30psi instead of the normal 55psi for up to 2000km at a time without any problems with tyre wear, but of course the maximum driving speeds were way down as well.

All that said, a vehicle with dual wheels is the worst possible vehicle for off-road driving. Traction seems poor (which might be why my Ford has two massive tow rings on the front and nothing at all on the back) and there is the constant worry of getting rocks caught between the tyres. Happened once on the Airstream - which was obvious because of the hopping and clunking, but the once on the F350 was only noticed at a coffee stop. Getting the rocks out was a major job too.

For on the road you have to keep the pressure that high , so no part of the rubber gets to warm so it hardens and damage is done at next bendings of the rubber.
I did some research of how low the tire makers dare to go, and made topic of it.
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/27477930.cfm

Most important is that you determine the weights on the seperate tires accurate, and that is best don by weighing in the loading you drive.
Then you have to give the speed you wont go over for even a minute in your situation.

Then I can calculate the needed pressure and even can give a range in wich the tires are save and no terrible bumping.
That is to system of the tire makers, as far I have found out right.

Need from tires maximum load and loadkind ( fi E-load) to determine the AT-pressure ( for E-load 80 psi), and the speedcode or maximum speed of tire.

Airing down is not a problem. We do it at the beach all the time, TC's, Class A/C's...yep even the 19.5 guys air down...Beach length is about 4.5 miles.

I usually go to about 25 on my current rig. But '02 F350 with my AF 860(about 1000ish pounds lighter) and in softer sand I'd take them down to about 18.

someone sended me pictures of Michelin tires information.
Special there is that for on sand the pressure can be lower then for on track and on its turn track lower for on road.
Its given in French and English , but in KG and bar
Am researching it to see if for on road the 1 Loadindex step higher for 10 km lower speed also goes for the lower pressures.
For on sand 20 km/h is given wich is about 12.5M/h.
For on track 65 km= given as maximum speed wich is about 40 m/h.

I understood from TS opening post that he wanted to know how low he can go , so you dont need to fill to much when goin on road from of-road . so the lowest pressure wich dont damage the tires for the eventually small trip home. Answer is , if you use for that a low enaugh speed , you can go pretty low.
In time I will put it in a spreadsheet and then I can converse it to psi and LBS for you .
I know these are probably not the tires you use , but if the maximum load of your tires is by accident the same , you can use the list.

egarant wrote:
I've hand plenty of experience letting air out of my tires when going through sand or washboarded roads, but never with a dually loaded to the truck's GVWR (14K) with a TC.

My fronts run at 80psi and each tire in the rear run at 65psi (door jam recommended tire pressures) during highway driving.

How low has anyone gone with THAT kind of weight on the back?

I want to hear from the HEAVYWEIGHTS out there! One ton +

Bad roads or offroad on forest service roads I'd not let any air out.

For real sand like at the beach and you need to float on top of it, I go down to about 30 for the 2 or 3 miles at low speeds for sand camping at the dunes. Doesn't matter if the rear duals are touching, only going like 5-10MPH for 2 miles. Front I take down to 30 ish also. Just make sure you have air for airing back up as soon as you hit pavement. I have on board air an a Powertank for airing back up.

Good evening Everyone.

2002 Ford F350 4x4 extended cab 8ft bed with a very heavy brand new Lance 1172

I am on my 2nd set of Michelins - LTX 235/85/16 and air them up to 80 pounds cold. All 6 of them! They stay at 80 psi all the time unless I am airing down for the beach.
At the beach I have my auto-deflators set for 35 pounds when I air down.
My first set of Michelins - I got 82k out of them with a 6 tire rotation every 4000 miles. I could have gone 90k based entirely on thread wear but they were 6.5 years old and showing some cracking around the bead.
My current Michelins are only 3 years old and I have 49k on them as we speak. If everything works out - I want to break that 90k millage on my LTX2 tires
Mike Tassinari

Some very good answers so far. I started writing this a while ago so there may be more since then!

This is one of those questions, don't you wish you could hear the answer to this very question from the perspective of someone like a Camel Trophy/Land Rover guy as well as from a Toyo tire manufacturer rep? I heard the answer to the topic question from a trainer from Land Rover at the Overland Expo in a class on tire pressure. I also then had the conversation with both the Land Rover guy AND the Toyo rep after the class was over.

The initial question was asked by the trainer to the crowd....."how low would you go if you were in conditions that warranted it, I.e. You are stuck in the Sahara in sand and need to get it going."

There was a lot of silence, and I finally spoke up and answered from the back of the crowd "it depends". He turned to me and said "depending on what?" I said, "it depends on the kind of tires I had on my vehicle and what vehicle I was in. I drive a 19,000 GVWR dually with 19.5" tires, which cannot be lowered essentially, at all." To which he said, "no. I would lower my air pressure to whatever it took to get out of the sand I was stuck in. Deal with getting it refilled if necessary later as soon as I got out of the situation."

I decided it wasn't worth interrupting him to try to explain about 19.5" tires (and the other .5" rims sizes/designs. So I nodded and let him go on with his class, which I have to say was EXCEPTIONALLY GOOD......I will fill in more about that class later. The point is I did not want to get into a side discussion about 19.5" tires and their inability to be lowered. Damn near nobody is overland exploration vehicles use .5" rim sizes.

He answered me and said "I would lower my air pressure to whatever it took to get out or to verify being completely unable to get out or get across the sand etc. The correct answer from the scenarios and tires he is knowledgable about.

The class was awesome, but during the class he pointed out the rep that was there from Toyo.....I then realize we are doing the class in front of the Toyo 18 wheeler marketing truck. I know this guy is going to know what I was talking about when I said 19.5" tires can't be aired down. I also know I almost bought 19.5" Toyos......can't remember the number but 608z or something? So I bide my time and enjoy the awesome class, and hang out afterwards, and eventually it's just me and the Toyo guy and the Camel Trophy guy. I answer to the instructor about how 19.5" tires have a different rim edge.....has a different angle, and I think a groove that holds the bead. I ask the Toyo guy to confirm that you literally can't lower the pressure in the 19.5" tire effectively at all it at least below about 70-80 PSI which doesn't help you extricate yourself from being buried in the sand. He says to both of us, "yep, he's right". The Camel Trophy guys says "huh. Oddball tire..." Exactly right. And not really applicable to Sahara desert exploring, but for me, CRITICALLY important.

My point is the answer, for us greater than 1 ton or 1 ton + crowd....is "It depends!"

19.5" answer, something like 60 PSI? My Michellin 19.5's was 80 I think. Not sure about my Hankook DH01's that I ended up with.

Here's the thing: if I had 16's or the standard up to "one ton" tires/rims, I would take the Camel Trophy dude's answer to me, in front of the whole class:

"However low I had to to get out of the 'stuck in the sand' and worry about airing back up AFTER I got out." In other words, now I that am not trying to move 5 feet, but rather, run down the road. For that, you better freakin have a way to air your tires back up. But if this were the situation, heck yeah, "ID AIR IT DOWN TO WHATEVER IT TOOK TO GET OUT including if the dually tires were touching. Who cares if they touch, if you are moving 5'! If it gets you moving and you drive 5 miles an hour no problem. But the moment you get back to hard pack or PAVEMENT then I either you keep going at 5 MPH or you get it aired back up. Highway speed with the duallies touching, no way!

If you want to air down a dually, one ton or greater it depends on:

What tires? 19.5's, basically none. If I can't get out of the sand, it's the winch, or help from another vehicle, it's jacking it up and laying boards or rock or carpet or that stupid green AstroTurf or riding the dirt bike out to get help???

With 16's or any wheel capable of being lowered without de-beading (a much bigger issue) "as low as it takes even if the duallies are touching! That might even help floatation, but once they touch you might lose effectiveness.....in other words I'd got AT LEAST until the duallies touched, maybe more. To get unstuck or back to the main road!

Hope this reads OK, that little cell phone screen is tough!