There may be some recommendations somewhere on the van or in the book, if you have one.
You have to have enough pressure to make towing easy with not drag caused by low tyre pressure. Not over-inflated, as the van may buck about and tyre wear will be uneven. Somewhere in between too flat and too tight. Now that's stating the bleeding obvious, isn't it?
If your plates and vegemite are bouncing out of the cupboard you haven't packed them tight enough. These things do not determine how tight your tyres should be.
Pack things close to reduce movement and shaking. I'm assuming you are using the on-slip matting in your cupboards, and maybe between items. The tighter things are packed, the less movement and risk of plate concussion causing breakage.
Stack and pack, and if you can't stop the movement, jam towels and tea towels in the cupboards to reduce movement of items.
Some roads are just too rough, and the vegemite will jump out of the cupboard anyway.
I have 50 psi in all 4 light truck tyres under my 20ft van, fully laden with all my wordly goods. I have no idea what the gross weight is, but I'm estimating about 2.5 tonnes with both water tanks full. The van tare is 1.5 tonnes.
Keep an eye on tyre wear, and you know what to look for if they're under of over inflated?
Cheers Chris

Well, as with most things to do with caravanning there almost as as many opinions as there are caravanners when it comes to tyre pressures. 

In my experience of sealed road driving .... My van tandem axel van compliance plate says that the tyres should be inflated to 200 (circa 29psi).  So I did for a hell of a long time.  These days I go a bit higher to around 250 or 36psi because I have my van loaded to the max, I think.  I find that this pressure ensures that the van tracks well with reasonable fuel economy & nothing breaks or falls off shelves .. eg. my toaster, jug, fruit baskets etc sit on the anti slip matting & never fall off.  However we do not go off road.   After 80,000km I changed the tyres because of age not wear.
 
A friend had a similar van and inflated to the dealer recommended 350/50 psi.  He complained that on the undulating surfaces on a trip with us thru  Qld to WA that the van was very unstable.  He dropped the pressure down to around 250/35psa with a remarkable improvement in towing.

I spent a lot of time talking to the van/tyre manufactures etc about the best tyre pressure & just got conflicting views.  Most of all  I decided too, that advice like mine from chat forums is best just taken on face value.

I think that previous advice about packing of stuff is the most pertinent.  In my van everything has a place .. so that it is close at hand when needed, doesn't require special packing when moving on & won't get broken in transit.
eg. glasses are in those wire brackets screwed to the walls, plates are in wire racks just like the display shelves in supermarkets ... all surfaces are lined with anit slip matting.  I have not had anything break in 10 yrs & 150,000km  .. except when pounding a glass on the trable to emphasise a point .. like ..  'what is the optimum van tyre pressure?'


happy travelling

Mike, thats a good point about matches. People should take note of it.

When doing search and rescue for the airports, we had a 747 do an emergency landing, as they just found out, a passenger had a carton of matches in their luggage.

Dave, even people in the tyre & mechanical industry give different opinions on what your tyre pressure should be.   I don't consider myself a know all so I hope you are not referring to me, I am just stating my opinion based on my personal experience and information put out by the tyre industry (eg; Bridgestone).

See this link, also click on Tyre Pressures and Tyre Marking plus the other side headings under Tyre Care which may be of some help to others reading this thread.

http://www.bridgestone.com.au/tyres/passenger/care/golden.aspx

Tell you a little story......years ago a friend of mine bought a camper trailer identical to the one I had.  The manufacturer had the pressure on the compliance plate of the trailer as 29PSI.  

I had the same tyres on my car and the compliance plate on the car said 34PSI,  I decided to run my camper trailer at 34 PSI the same as the car as the tyres looked underinflated to me at 29PSI.

I went all around Oz and when I returned my tyres did not even look like they had been worn, even tread all over.  My friend on the other hand also went around Oz and kept his on the 29PSI.  Both his tyres blew out and shredded on his trip.  Bear in mind we both had identical camper trailers and tyres.

Berg

The best way to do what suits your circumstances is to feel all your tyres when you pull up for a pit stop. If the tyres are hot add more air.
Like Dave and I said start with the compliance plate.
The vehicle will be fairly easy, as you'll feel it as you drive. The towed vehicle will be a bit trickier and the feel test is pretty good. You don't have to add tonnes of air, just eg 4psi at a time.
If the towed tyres are underinflated you will feel the drag, and see it on the fuel guage.
Much of this is decided by how much weight you have in both vehicles. Start with commone sense, and then work on trial and error, within reason.
I too have used my own experiences as my reference.

Basil Faulty wrote:

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Granny is on the money, the 4PSI add/subtract rule of thumb ( ROT) seems to work. Just make sure there is air in them, I have the indicating dustcaps on my van, dirt cheap from Supercheap....

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Hi Basil,

The 4PSI Rule and other good info is also shown on the link I posted earlier on this thread;

Tyre pressure tips

Contrary to popular belief, tyre pressure is not determined by the type of tyre or its size but
upon your vehicle's load and driving application i.e. speed

To find out what your car's tyre pressure should be, consult the manufacturers tyre placard usually found inside the driver's door sill, glove box, fuel filler cap or under the bonnet.

The placard also displays the manufacturers recommended tyre sizes.

Tyre pressures should be checked when the tyre is 'cold', as pressure increases as the tyre becomes 'hot'.

Take the "cold" reading and check them against the recommended tyre pressures from your placard.

Heavy loads or towing puts an extra strain on your tyres. So if your vehicle is fully loaded with passengers and luggage, the general rule is to add 28kpa (4PSI or 4lbs).

At high speed, (defined as driving at 120km/h for over one hour), your tyres will wear out twice as fast as when you drive at 70-80 km/h. If your tyres are under-inflated by twenty per cent tyre life can be reduced by thirty per cent. The rule here is to add 28Kpa (4PSI) from your Minimum Compliance Plate Pressure. Don't inflate your tyres above 40 psi or 280 kPa. When the tyres get hot from driving, the pressure will increase even more.

Believe it or not, checking your tyre pressure can have a big impact on our environment. An under-inflated tyre creates more rolling resistance and therefore more fuel consumption. By keeping your tyres inflated to their proper levels, you can help maximise your car's fuel economy and minimise its impact on our environment.

 

..............................................................
Basil,

In regards to the valve cap indicators;

How do those indicators work, do they show a general indication eg; fully inflated, half, quarter etc according that what they are, or do they give the actual tyre pressure at the time they are read?

Thanks
Berg

 

-- Edited by Bergholt on Monday 18th of May 2009 02:00:38 PM

-- Edited by Bergholt on Monday 18th of May 2009 02:06:41 PM

hi.   first thing is to contact the tyre manufacturer,  they will guide you.         tell them how you are operating the rv ( approx weight of the vechile loaded,and the daytime temperature.  what your average speed is and what ply rating the tyres have.             with trucks we have found that if you can get them to run within 2 pounds pressure they will wear evenly,and run cooler)  kind regards and happy motoring

kenmarg wrote:

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hi.   first thing is to contact the tyre manufacturer,  they will guide you.         tell them how you are operating the rv ( approx weight of the vechile loaded,and the daytime temperature.  what your average speed is and what ply rating the tyres have.             with trucks we have found that if you can get them to run within 2 pounds pressure they will wear evenly,and run cooler)  kind regards and happy motoring

Hi Ken and Marg, is that 2PSI more or less ?  Thanks for the tip also on pressures, sounds like good advice.   Regards Berg
PS:  Will be away in Cunderdin for a few days, will not read your reply until my return.

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