John,

Whenever I suggest to outback travellers to drop their tyre pressure they in turn suggest that I should be in the funny farm. (Possibly true anyway).

I always carry a high quality/efficient compressor and regularly adjust pressures to suit. And speed.

Mike.

Many caravan travellers could be hammering their vans into an early grave and costing themselves thousands of dollars in repairs and lost resale value by not lowering tyre pressures when they leave the bitumen.

They have it all wrong, in my view.

The primary purposes of reducing tyre pressures on rough or soft roads is to improve flotation and to protect the tyres from damage.

It is the suspension's job to 'take care' of the van and there in lies the main problem in that many/most vans have disgusting suspension.

Lowering tyre pressures will help the van survival a little, but it is really a bandaid.

 

This is Michelin data for the tyres I use on the OKA.

A 50% reduction in highway pressure is quite dramatic and bust be accompanied by a serious reduction in maximum speed (in our case it wequires a MAXIMUM speed of 20kph. Exceeding that will overheat the sidewall and destroy the tyres.

Cheers,

Peter

Peter_n_Margaret wrote:

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Many caravan travellers could be hammering their vans into an early grave and costing themselves thousands of dollars in repairs and lost resale value by not lowering tyre pressures when they leave the bitumen.

They have it all wrong, in my view.

The primary purposes of reducing tyre pressures on rough or soft roads is to improve flotation and to protect the tyres from damage.

It is the suspension's job to 'take care' of the van and there in lies the main problem in that many/most vans have disgusting suspension.

Lowering tyre pressures will help the van survival a little, but it is really a bandaid.

Cheers,

Peter

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Gday...

Interesting how some statements get taken verbatim rather the understanding the intent of the advice. 

Yes, it is the suspension's job to "take care" of the van ... springs to allow the 'shock' to be 'absorbed' and the dampers (shock absorbers as we call them here) to keep the springs' movement controlled.

However, a tyre pumped to 55psi is going to be much 'harder' and far less flexible than a tyre at 25psi - 'road shocks' will be transmitted directly to the suspension. These pressures are very sensible for driving on sealed roads at 80-100kph.

However, if driving on unsealed (rough) roads that pressure will be FORCING the suspension to "do its job". This will cause the springs to be forced to flex considerably, and constantly, and the damper (shocker absorber) to be subjected to considerable up and down motion ultimately overheating the oil and losing its ability to dampen the 'road shock' and FORCING the suspension to NOT be able to 'do its job' ... transmitting the road shocks directly into the van's frame and internals.

Conversely, a tyre at 25-30psi, with the additional wall flexibility, will - in itself - absorb a considerable amount of the road shock BEFORE it is transmitted to the suspension - allowing the springs and dampers (shock absorbers) to work less arduously and continue to 'do its job' for a considerably longer time.

HOWEVER, IT MUST BE REALISED THAT IF TYRE PRESSURES ARE REDUCED TO THESE PRESSURES THEN THE SPEED OF THE VEHICLE/VAN MUST BE MUCH SLOWER.

As stated in the article, if running 25-30psi then road speed should be 65-70kpnh so that the tyre walls, which will now flex more, are not subjected to overheating. Personally I would travel closer to 50-55kph.

This advice to lower tyre pressures AND SPEED for unsealed (rough) roads applies equally to the vehicle as much as it does to the van.

Cheers - John

Well where I live and farm we drive over corigations on a daily basis never let a tyre down yet it is the suspensions job to smooth out the bumps the tyre is simply a vessel to hold the air required to support the load placed upon it and maintain contact with the road if you run low preasurs it will destroy the walls of the tyre in no time this may be a sulotion for a very short time in order to get yourself out of a bog or across some loose sand but not for sustained travel it will shorten the life of your tyres substancialy they are not designed to carry a load with lots of side wall flex
The weight ( load ) on the tyres is a very important consideration tyres are not designed to carry weight without the proper air preasurs in them
Ok having said that I think the basis for this topic is to make the road easier on the van and contents and this is understandable but just remember that as with a lot of things in life it is a trade off on this occasion between saving the van and contents and getting a good life out of your tyres

Aus-Kiwi wrote:

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Be aware of low Sh profile tyres ... Dropping pressure in them is leading to tyre pinching or rim damage .
We cover a lot of distance in Australia.. Personally I wouldn't run lower than 35lb ..
Depends on weight ? Look at tyre placard inside door ..

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 Totally depends on your tyres, and the weight you're putting on them. I have 267/75/16 on the troopy and have no probelm dropping them to 25psi when the need arises. And I'd even go lower on soft sand.

Aus-Kiwi wrote:

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03_Troopy wrote:

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Aus-Kiwi wrote:

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Be aware of low Sh profile tyres ... Dropping pressure in them is leading to tyre pinching or rim damage .
We cover a lot of distance in Australia.. Personally I wouldn't run lower than 35lb ..
Depends on weight ? Look at tyre placard inside door ..

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 Totally depends on your tyres, and the weight you're putting on them. I have 267/75/16 on the troopy and have no probelm dropping them to 25psi when the need arises. And I'd even go lower on soft sand.

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 Yes correct .. What I'm saying is be aware over long distances And be aware of speed..75 series  is quite a high proiled tyre.. Compared to what can be fitted to road cars ..  the last thing you want out bush is tyre wall failure ..

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 Out bush, why would you want to have low profile tyres?

It probably be pretty crap driving your drag car off road anyway mate.

Woody n Sue wrote:

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Well where I live and farm we drive over corigations on a daily basis never let a tyre down yet it is the suspensions job to smooth out the bumps the tyre is simply a vessel to hold the air required to support the load placed upon it and maintain contact with the road if you run low preasurs it will destroy the walls of the tyre in no time this may be a sulotion for a very short time in order to get yourself out of a bog or across some loose sand but not for sustained travel it will shorten the life of your tyres substancialy they are not designed to carry a load with lots of side wall flex
The weight ( load ) on the tyres is a very important consideration tyres are not designed to carry weight without the proper air preasurs in them
Ok having said that I think the basis for this topic is to make the road easier on the van and contents and this is understandable but just remember that as with a lot of things in life it is a trade off on this occasion between saving the van and contents and getting a good life out of your tyres

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Agree with comments above plus Peter's comments regarding van suspensions. The suspension was the FIRST thing I looked at when purchasing a van.

So many people asked what I was doing going around Brissy van show 3 days in a row in 2005. I told em where to start and look UNNDER first and at inside LAST as most manufacturers will have an interior to suit you or will ensure they change it to your needs.

It really is simple IMHO - what's under the van keeps you safe, not the nut behind the wheel,,lol.