Sometimes even a solid platform isn't enough - BBC article about a family traveling in Australia

[billiebob]

Hopefully this is allowed here but the linked article is about a poor family whose rig bogged in the outback.

https://www.bbc.com/news/world-australia-59301237?xtor=AL-72-[partner]-[bbc.news.twitter]-[headline]-[news]-[bizdev]-[isapi]&at_campaign=64&at_custom2=twitter&at_custom1=[post+type]&at_custom3=@BBCWorld&at_medium=custom7&at_custom4=C44B2650-4717-11EC-BBAC-26B7BDCD475E

Given that we all could end up like them, is there any particular skill one could have used here? Aside from don't try this at all

I've been stuck enough times in my Jeeps to know that sometimes you are just done and need help. But given where some of us planning to go, help is often a long way away. Love to hear about skills others would use given the above scenario. At least this family looked about as prepared as you could get and nobody was really at a huge risk.

In this particular case the roads were closed...... that might be a good skill to have. Read.
Listen to the weather. Do historical weather data checks. Is there a monsoon season, a hurricane season......
Talk to the local outfitters, forest rangers, search and rescue. PLAN yer trip don't just get in the truck and drive.
Then here is political stability
Watch the news, stay current, don't get bogged down in your world travels and ignore the world.
Cuz a country in turmoil won't ignore you

Not that it is fool proof, but travel the path of least resistance, use the go arounds, don't insist on making progress when the land looks deceivingly stable. Research the geology of the land you are entering. AND consider the "what if" senario.

Beyond all that there are insurance policies/companies which/who will come and rescue you when the world comes tumbling down. If civil war breaks out they WILL get you and yours to safety.... likely deserting everything but the clothing you are wearing.

Know the language, overlanding should be a cultural experience, every day you should interact with the locals.
Stop and talk. AND LISTEN !!!! More than telling them about you....... some of us are far too good at that..... learn the skill of conversation and LISTEN.

 

[clydeps]

After lowering the pressure you have a footprint of 10" x 40"

I realise you weren't trying to give exact numbers, but you would need one hell of a big tyre to get a footprint 40" long. Even at minimum pressure the footprint length is not going to be any more than maybe 1/2 of the tyre diameter at max.

The pressure inside the tyre is always going to be roughly the same as the pressure on the ground because that's what's holding it up - the difference will be due to sidewall stiffness. So 40 psi inside the tyre,1000 lbs weight gives a footprint of 25 sq in or so, i.e. 2.5" long for a 10" wide tyre. Drop it to 10 psi and you would have something like 10" length.

 

[Peter_n_Margaret]

These are not "emergency extraction" pressures, and the sidewall does not contribute unless in soft conditions, but the footprint increase with lower pressure is clear.
My pics, Michelin published data,

Cheers,
Peter
OKA196 motorhome

 

[Todd780]

These are not "emergency extraction" pressures, and the sidewall does not contribute unless in soft conditions, but the footprint increase with lower pressure is clear.
My pics, Michelin published data,
View attachment 693203
Cheers,
Peter
OKA196 motorhome

Peter,
This is a good picture of the tired deflated. It looks to have around 3 to 4 times the footprint of the tire at highway pressure. The important thing is you do NOT want see a wrinkle in the tire at the #5 and #7 position. You do NOT want the wrinkle in the tire.

To keep it simple;
If the normal tire footprint (contact with the ground) is a 10" X 10" = 100 square inches of contact area. At the weight is 1,000 pounds on the tire. You would have 10 pounds per square inch.
After lowering the pressure you have a footprint of 10" x 40" = 400 square contact inches. At the weight is 1,000 pounds on the tire. This will then give you a 2.5 pounds per square in weight.
The less weight the risk of sinking in is reduced. This never guarantees that you will not get bogged down or be able to get out if your already stuck. It gives you a better chance.

Thanks for sharing your photo Peter!

Da Frenchman

Lots of good info. Thank you!

 

[charlieaarons]

I can deflate to <24% road pressure from inside the cab; need to activate switch turning off CTIS computer to manually deflate further.
Unfortunately the equation relating footprint to psi isn’t linear, because sidewalls have nonzero stiffness, and tires have a finite size. I know from published Michelin data that on 395s for example, 40% pressure increases footprint by 1.55; not 2.5! 24% might result in 2.5, but not 4. Reductio ad absurdum (aka boundary condition): Zero psi doesn’t give footprint of infinity.
And the risk of debeading isn’t just theoretical. When Unicat took us to Morocco when we picked up the truck, I debeaded at about 25% crossing a very muddy creek/ditch. Both tires on one axle since they’re connected by CTIS system unless you manually disconnect hoses. Fortunately they were a big help doing the dirty work. That’s when I discovered MB had literally forgotten the beadlocks that are standard with 395s + CTIS. They were kind enough to deliver them to my house eventually, gratis. But internal beadlocks are virtually impossible to install in the original Lemmerz wheels without an enormous hydraulic press, which is one of the several reasons I like Hutchinsons.