Caravan Tyre pressure on dirt roads

RobDor · Veteran Member

Caravan Tyre pressure on dirt roads

Peter_n_Margaret · Guru

Get the tyre manufacturer's data.
I would start by dropping the pressures by 30%, but you MUST also drop the max speed to around 60kph.
Too much speed will overheat the tyres and destroy them.
Get yourself an infrared thermometer and check the sidewall temperatures. Don't let them exceed 70c. If they get hot, slow down.

ps...67psi is very high. The tyres are clearly too small for optimum travel on gravel roads.
Cheers,
Peter

Nevd · Senior Member

I have a single axle 2600 van. Run same highway pressures as you. Queried on their facebook page and the dealer (uses his products regularly offroad) and experienced vanners all said 25 - 30 PSI - no more - and of course, drop your speed to suit

Whenarewethere · Guru

We don't tow.

But for the car, our car states 32psi, we drop the car tyres about 30%, if looks like a good dirt road probably about 25%. Also limit speed to 80kph so tyres don't overheat.

If it is a really crap road we stop more often to let everything cool down.

Bobdown · Guru

What do you mean by 'dirt roads'? I wouldn't drop the tyre pressure on gravel roads at all, just drop your speed.

On beach sand, I would drop to 30psi on the van and around 20 psi on the tug.

As said 67 psi is high, but you obviously have done your homework and have had that queried before.

Cheers Bob

Whenarewethere · Guru

For instance, if you go into Purnululu NP there is a sign recommending to drop 10psi below normal highway pressure.

Francois Peron NP they ask you to drop tyres to 20psi.

They are both quite decent roads.

Going north from Karijini NP, we were advised not to use the public road as it was a really shocking road, & use the mining road & get a pass.

We used the public road, let tyres down, it was a great road, only drove 80kph. Glad we did as there were these very occasional sharp rock edges across the road that were impossible to see.

If nothing else, it is just a more comfortable ride, & it only takes us a few minutes to air up.

RobDor · Veteran Member

Thanks for the input. Wasnt sure about letting pressure down on dirt roads, but sounds like maybe doesnt need it, just slow down, take it easy to start with. Yes, 67psi is correct pressure for these tyres and they are not small, decent heavy duty tyre actually.

Peter_n_Margaret · Guru

RobDor wrote:
Thanks for the input. Wasnt sure about letting pressure down on dirt roads, but sounds like maybe doesnt need it, just slow down, take it easy to start with. Yes, 67psi is correct pressure for these tyres and they are not small, decent heavy duty tyre actually.

Reducing pressure provides improved protection against damage form the occasional rock. Like poking a finger into a hard baloon and a soft baloon. One will burst, the other won't .

It is not the tyre construction that determines the required pressure it is the footprint on the ground and the weight carried.

Either the footprint is small or the weight carried is large or you have the pressure wrong. There is no other option.

Cheers,

Peter

RobDor · Veteran Member

I use this calculator for tyre pressure - http://www.gnschassis.com.au/tyre-pressure-calculator/
Heres a couple of pics of tyres and calculates to 67 psi. Rides along very well.

Peter_n_Margaret wrote:
RobDor wrote:
Thanks for the input. Wasnt sure about letting pressure down on dirt roads, but sounds like maybe doesnt need it, just slow down, take it easy to start with. Yes, 67psi is correct pressure for these tyres and they are not small, decent heavy duty tyre actually.
Reducing pressure provides improved protection against damage form the occasional rock. Like poking a finger into a hard baloon and a soft baloon. One will burst, the other won't .
It is not the tyre construction that determines the required pressure it is the footprint on the ground and the weight carried.
Either the footprint is small or the weight carried is large or you have the pressure wrong. There is no other option.
Cheers,
Peter

RobDor · Veteran Member

RobDor wrote:
should have added, van weight is 2600kg

I use this calculator for tyre pressure - http://www.gnschassis.com.au/tyre-pressure-calculator/
Heres a couple of pics of tyres and calculates to 67 psi. Rides along very well.

Peter_n_Margaret wrote:
RobDor wrote:
Thanks for the input. Wasnt sure about letting pressure down on dirt roads, but sounds like maybe doesnt need it, just slow down, take it easy to start with. Yes, 67psi is correct pressure for these tyres and they are not small, decent heavy duty tyre actually.
Reducing pressure provides improved protection against damage form the occasional rock. Like poking a finger into a hard baloon and a soft baloon. One will burst, the other won't .
It is not the tyre construction that determines the required pressure it is the footprint on the ground and the weight carried.
Either the footprint is small or the weight carried is large or you have the pressure wrong. There is no other option.
Cheers,
Peter

Peter_n_Margaret · Guru

Your pics clearly show that that tyre has a maximum load of 1550kg each at a maximum of 60psi.
At 67psi it is dangerously over pressure.

I assume it is a tandem axle van?
There are 4 tyres carring a total of 2,600kg. That is 650kg each.
When I enter your figures into the calculator that you provided it says that your tyre pressures should be 25psi.

How did you conclude 67psi?
Cheers,
Peter

yobarr · Guru

Peter_n_Margaret wrote:
Your pics clearly show that that tyre has a maximum load of 1550kg each at a maximum of 60psi.
At 67psi it is dangerously over pressure.

I assume it is a tandem axle van?
There are 4 tyres carring a total of 2,600kg. That is 650kg each.
When I enter your figures into the calculator that you provided it says that your tyre pressures should be 25psi.

How did you conclude 67psi?
Cheers,
Peter

Hi Peter.Whilst I don't remember the exact figures,when I visited Rob's home in Cairns to help him with getting an ATM upgrade,I also did all the figures for his tyre pressures etc,and it all seemed OK.He has a single axle off-road type van at 2600kg and his pressures were correct,according to the calculation that I use.Perhaps Rob could post his tyre details so you too can give an opinion,but unfortunately I don't recall details.Rob is being very responsible in safely and legally setting up his van,so will be receptive to your assistance.Cheers

Peter_n_Margaret · Guru

There is no way that this tyre can safely run at 67psi.
If it is a single axle van, that makes the appropriate highway pressure about 50psi.

UNLESS I am misreading that 60psi and it is really 80psi???? That is a seriously high pressure for a passenger tyre.

Cheers,

Peter

EDIT.... 560kpa translates to 80psi, so I need to appologise to the OP.

I would be interested to know the tyre size and load rating.

-- Edited by Peter_n_Margaret on Sunday 20th of February 2022 08:25:40 PM

yobarr · Guru

Hi Peter.The tyres that Rob is using seem to have the same load specs etc as the tyres that I have on my car.They are 16 inch with 1550kg maximum load (Rating E) and 80 psi maximum pressure.Cheers

-- Edited by yobarr on Sunday 20th of February 2022 08:35:09 PM

Peter_n_Margaret · Guru

They are 265/75R16. Going to 285/75 or 305/75 would reduce pressures usefully.
Cheers,
Peter

watsea · Guru

In an enlargement of the photo that shows the whole wheel rim of Rob's wheel, it is possible to read that the tyre is a light truck type.

RobDor · Veteran Member

Peter_n_Margaret wrote:
Your pics clearly show that that tyre has a maximum load of 1550kg each at a maximum of 60psi.
At 67psi it is dangerously over pressure.

I assume it is a tandem axle van?
There are 4 tyres carring a total of 2,600kg. That is 650kg each.
When I enter your figures into the calculator that you provided it says that your tyre pressures should be 25psi.

How did you conclude 67psi?
Cheers,
Peter

Youre mistaken. its actually 80psi, not 60psi. Cheers

RobDor · Veteran Member

watsea wrote:
In an enlargement of the photo that shows the whole wheel rim of Rob's wheel, it is possible to read that the tyre is a light truck type.

Yes correct. I recently had an ATM upgrade on the van and all that was thoroughly checked by certifier before getting blue compliance plate. Cheers

Hitting the road · Senior Member

Wow...that is exactly why I opted for a tandem axle van...with a manufacturers GTM of 2503kg it equates to a load per tyre of 625.75kg's. My tug has a GVM of 2949kg, 737.25kg's per tyre properly loaded.

I would feel decidedly uncomfortable asking a tyre on my van to carry 1350kg plus...adding the inevitable additional sway that a single axle van will have generating extra heat.
At the very least if I do pop a tyre there should still be one good one holding up the van on that side reducing the chance of a rim digging in and causing me additional drama and damage. Though I am sure the manufacturers have done serious calculations as to safety levels of tyre / rim / bearing requirements. Light Truck type tyres would be mandatory on any van.

I understand why some people opt for a single axle. Though it seems the single axle "Hybrid" type vans are getting much heavier with more and more luxuries being added. I have seen single axle vans with potential GTM's pushing 3000kg!

RobDor · Veteran Member

Theyre a light truck tyre designed for the job and running well within tolerance, so its not an issue.

Peter_n_Margaret · Guru

RobDor wrote:
Theyre a light truck tyre designed for the job and running well within tolerance, so its not an issue.

I agree that it is not overloaded. There are tyres to carry any load. My single axle off road trailer has the same tyres as the OKA, so the tyres are are good for over 6T.

On poor roads touugh it is preferable to operate at lower pressures, so larger diameter, larger section tyres have a distinct benefit.

Cheers,

Peter

Hylife · Guru

Peter_n_Margaret wrote:
There is no way that this tyre can safely run at 67psi.
If it is a single axle van, that makes the appropriate highway pressure about 50psi.
UNLESS I am misreading that 60psi and it is really 80psi???? That is a seriously high pressure for a passenger tyre.

Cheers,
Peter

EDIT.... 560kpa translates to 80psi, so I need to appologise to the OP.
I would be interested to know the tyre size and load rating.

-- Edited by Peter_n_Margaret on Sunday 20th of February 2022 08:25:40 PM

That tyre can safely run at 80PSI !!

always use the single pressures, in your pic its 80PSI.

The double is for side by side like a truck rear axel, not a tandem van.

Same as my van's tyres, 80PSI at 1550kg, so mine run at 68PSI

-- Edited by Hylife on Wednesday 23rd of February 2022 09:49:16 PM

Hylife · Guru

RobDor wrote:
Howdy, will be heading off soon and doing some dirt roads west of Cairns to the gulf. I have a single axle caravan at approx. 2700 ATM. I run the tyres at about 67psi for normal driving. No need to go over what pressure I should run etc. have been through all that and 67 is correct. My question is, what pressure should I drop it to when on the dirt roads ? Assuming I need to still keep it at a safe level and handle the road surface a bit better ? is there a 'rule of thumb' for dropping the pressure ? such as a % I should drop it by ? thanks for your input.

Mine on the van run at 68PSI normally and the car 38front and 45 rear .

On bad corrugations I drop mine on the van to 40, and the car down to 25 and 30.

And slow the h#ll down on sh!t roads when you have lowered pressures.

-- Edited by Hylife on Wednesday 23rd of February 2022 09:54:05 PM

RobDor · Veteran Member

Hylife wrote:
RobDor wrote:
Howdy, will be heading off soon and doing some dirt roads west of Cairns to the gulf. I have a single axle caravan at approx. 2700 ATM. I run the tyres at about 67psi for normal driving. No need to go over what pressure I should run etc. have been through all that and 67 is correct. My question is, what pressure should I drop it to when on the dirt roads ? Assuming I need to still keep it at a safe level and handle the road surface a bit better ? is there a 'rule of thumb' for dropping the pressure ? such as a % I should drop it by ? thanks for your input.
Mine on the van run at 68PSI normally and the car 38front and 45 rear .
On bad corrugations I drop mine on the van to 40, and the car down to 25 and 30.

Thanks, good to know. That is basically identical to my normal tyre pressures on van and car, so will do a similar thing. Appreciate the input, cheers
And slow the h#ll down on sh!t roads when you have lowered pressures.

-- Edited by Hylife on Wednesday 23rd of February 2022 09:54:05 PM