Off Road Tire Pressure - How Low Do You Go?

[smlobx]

Depends on terrain.

Outer Banks National Seashore (everything from deep sand to hard pack) I've gone as low as 28psi in the rear, 30psi up front on my LRE Toyo ATII 295-16s on my F250.

Normal tarmac psi is 65 and up to 75 if pulling the boat with camper in the bed. 80 psi is max; embossed on sidewall.

The important thing to remember...
You must air up before driving normal highway (tarmac) speeds after airing down. PSI represents a given volume of air in the tire carcass. Not enough air and the tire will very quickly over-heat resulting in excessive wear and possibly failure at highway speeds.

I use this little pump to air up.

As Advmoto will attest driving on the Outer Banks beaches is some the softest sand known to man. My trucks suggested pressures are 65 front / 70 rear. At the beach I will start airing down to 35/30 with a light truck.
I would imagine that most places out west you could easily get by with 50 or so in my truck off-road.

 

[Advmoto18]

...would require long run times for my Toyo AT II..265/75 x16 tires and this would generate a lot of heat...which the pump would handle in the short term...but heat is not the friend of a compressor.

Phil
I completely agree! It does get hot! But, I have never had it fail to inflate MilSpec, Toyo or my scoot tires.
Bill

 

[Advmoto18]

As Advmoto will attest driving on the Outer Banks beaches is some the softest sand known to man. My trucks suggested pressures are 65 front / 70 rear. At the beach I will start airing down to 35/30 with a light truck.
I would imagine that most places out west you could easily get by with 50 or so in my truck off-road.

Outer Banks is indeed a very unique environment!

Have you guys made a decision on a camper?

 

[brianjwilson]

An 8,000-pound rig will need higher pressure than a 6,000-pound rig, whether on the street or in soft sand. Chalking your tires is still the best way to determine correct street pressures in my opinion. Our 6,000-pound Tacoma/FWC likes 45 psi in front and 50 in the rear on the street; in soft sand I would not hesitate to go as low as one bar (14.7 psi). For most of our off-pavement driving, 25-30 psi all around works well.

It's really critical to have a good compressor, as well as an easy way to air down tires. If the process is a 30-minute epic you're a lot more likely to skip it. Proper airing down is good for everything—your comfort, the vehicle's well being, and the trail's as well.

I run about the same on my Tacoma/fleet on e rated tires. 45/50 or 45/55psi. I haven't been off road for extended periods with it yet, so have only aired down into the 30s for shorter off road trips. Just enough to soften the rid a bit, but I would expect high teens would still be plenty safe at this weight.

 

[Ace!]

I think you're less likely to puncture a tire or damage a wheel if you lower the pressure, not run higher pressure.

 

[Ace!]

Thanks for the link. I've considered a Viair for a long time but never pulled the trigger. My QuickAir2 is almost 20 years old and has never skipped a beat, but now that I'm running a little larger tires I decided to order the Viair 400P

 

[Wallowa]

Disagree...higher pressure protects the rim and wards off punctures.. part of that is because of heat from sidewall flex at lower pressures; the rest is just mechanical protection and load bearing over larger surface.. good reads on this topic are Chris Scott's books..."Sahara Overland" and "Adventure Motorcycling".

But hey we pick what works for us...

Phil

 

[Bajaxplorer]

'09 power wagon/hawk, 9,000 lbs loaded. Toyo ATII 12:50×17×35 tires. Run 55-60 psi on pavement and around 25 psi in baja off pavement and AZ desert. Tires have to flex to absorb washboard, and enlarge footprint to float on sand. Letting out a few lbs does not accomplish this. If I were to run more than 60 psi on roads, it would wear out the center of my tread in no time. When aired down I never exceed 45 mph.
BX

Sent from my SM-G900V using Wander The West mobile app

 

[ntsqd]

I think you're less likely to puncture a tire or damage a wheel if you lower the pressure, not run higher pressure.

That's a really big variable.

Going slow in soft terrain, yeah less likely to hurt something at low pressure. Not that high pressure is a risk except for getting stuck.

Going fast down a power line road or Saline Valley Rd or from Mex Hwy 1 to El Arco, Baja you'd better be at street pressures or higher.

Low pressure is also much more of a risk when running in the wet with sharp rocks. Rubber cuts much more easily when wet, just look up DIY tire siping videos to see the difference.

On the CTD I have hard mounted the compressor that I lucked onto in the junk yard. It's Thomas looking clone, but "Made in Chino" (I *think* that's what the now gone steeker said.... ) air ride compressor. I carry an MV-50 (or maybe it's a MF-1050, I dunno know any more) for back-up.

 

[Chips95]

2012 Power Wagon, I run 60 on the street and 30 off road, It seems to work for me and the wife prefers the softer ride on the washboard.

 

[Ace!]

Lower pressure allows the tires to conform to the terrain. You cut your sidewalls with high pressure. My post is about off road. On road, yeah, you'll over heat, but my post is about off road. Off road at 15 - 30 mph you're not going to over heat the tire. You'll gain an advantage at lower pressure in that the tire will absorb the jarring and conform to the hazards. High pressure cuts and pops.

 

[fish more]

BrianG, Your Dodge can be programmed to run lower air pressure. Look in your owners manual, it will instruct how to reset to the lower pressure setting.

 

[Wallowa]

I know that this is like beating the dead horse...

but off road with motorcycles or trucks at slow speeds you can get away with low pressure even if you are in severe rocky terrain, but even at slow speeds when the tire conforms to sharp edges on the "trail" it is much more likely to cut than if a higher pressure has strengthened the tire and it rides over the sharp edge...no doubt in sand or mud, unless again there are sharp rocks/ledges you can get away with and get more traction with lower pressures...same with rims, at some speed with low pressure you will contact a rim and possible damage it when you impact a solid object..true by slowing down even on ledges or traversing sharp rocks you can lessen or eliminate damage to tires or rims...but your speed, weight, tire plys/size all become more critical at low pressures..a little too much speed and not enough pressure and scratch that rim and perhaps the tire.

Sidewall and thread temp increases for a given speed...with low pressures on or off road the temp increase is greater causing not just increased risk of a failure of the carcass but by soften rubber makes it more susceptible to puncture...the higher the temp of rubber the softer it gets.

Look I am not trying sell anything...Scott and other Dakar etc racers [Tom Sheppard] pressure down only when they must, but otherwise run higher pressures to lessen punctures and protect rims off road.... when low pressures are absolutely necessary to maintain traction then of course you drop pressures, slow down and pressure back up as soon as possible...

To each their own...this approach has worked for me and I am just tossing it out for thought..

And as always...I could be wrong!

Phil

 

[Ace!]

Yep, to each their own (experiences).

 

[brianjwilson]

We aren't talking about hi speed off road racing, but general off road driving. If you think that more pressure off road is better you should really do some reading on the benefits of airing down.

Lower pressures allow the tires to conform and flex. When encountering a sharp obstacle, an aired down tire can deform around it rather than apply ALL the weight of the rig onto that one sharp edge. This allows for a better ride (less wear on vehicle and occupants), better traction, larger footprint and reduces the risk of punctures. Go ahead and grab to balloons. Inflate one to the max and inflate the other to half size. Poke them both with a tack or sharp rock and see what happens.

There are numerous benefits to airing down. Again do some research, watch some videos or whatever. As for sidewall gashes, a sharp, well placed rock will tear a sidewall wether you're at max pressure or aired down. If you're running around extremely sharp rocks regularly your best bet is running a tire with a very strong/thick sidewall. And of course using proper tire placement.

Here is one for you directly comparing punctures vs air pressure.

http://youtu.be/9Kz8mmLkeks


Some reading
http://www.expeditionswest.com/research/white_papers/tire_selection_rev1.html

 

[Happyjax]

New info for me. Thanks

 

[ntsqd]

snip.....
You cut your sidewalls with high pressure. My post is about off road. On road, yeah, you'll over heat, but my post is about off road. Off road at 15 - 30 mph you're not going to over heat the tire. You'll gain an advantage at lower pressure in that the tire will absorb the jarring and conform to the hazards. High pressure cuts and pops.

Not true, if it were off road racers would suffer from countless sidewall cuts and that simply isn't the case. The correct air pressure choice depends entirely on the situation and the driver, not some arbitrary hard and fast rule.

Off pavement I've been up to 80 mph in our CTD/camper and very close to 100 in my '91 Suburban. I danged sure wouldn't do that on low tire pressure.

There are some who air down at the edge of the pavement, shift into low range, and change neither regardless of the type of road, track or trail until they get to pavement again. I absolutely detest following these people and will pass them at first opportunity.

 

[Ace!]

You quoted my post where I specifically talk about low speed and then give a high speed example. Would you like some apples with your oranges? Yes, obviously, if you're on terrain that allows you to travel 100 mph you aren't driving in the conditions I'm asking about.

 

[Wallowa]

Sorry did not mean to turn this into a food fight..

Coopers are great tires; probably my next set of tires...but test was to sell Coopers....

Google "off road racing tire pressure"...see first post at "Race-Dezert.com" concerning tire pressures...they nominally run 35+psi in light weight Baja 1000 cars to prevent punctures [none during race]; cited higher number of punctures when pressure dropped to 28...I also re-reviewed Chris Scott's Sahara [then Dakar] advice and found the same recommendation....

Air down for slow deep sand, mud or snow if you must to keep moving but as weight or speed increase air back up...

Anyway I will withdraw from this donnybrook...do the Google search; very educational and with empirically gained advice...then decide.

Phil

Ps...Ace I want to read a trip report when you return! Have fun....

 

[Ace!]

I am making a point of taking two cameras. I don't normally take pictures, but I am really going to try to be more mindful and takes as many pictures as I can this trip (which means maybe a few ).