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Tyre pressure = Wt. Of ‘Van multiplied by Max.Tyre Pressure (stated on sidewall) divided by Max.Tyre Load (stated on sidewall) times number of tyres/wheels.

eg Wt. Of ‘Van   =  1400 Kg.

      Max.Tyre Pressure = 66 psi

      Max.Tyre Load  =  775 Kg.

    No. of tyres/wheels = 2   (or 4 if twin axle)

Quote: Originally posted by Angu2you on 07/6/2007

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THE INFORMATION ABOVE IS INCORRECT AND POTENTIALY DANGEROUS.

Tyre pressures stated on sidewall markings are not recommended running pressures - they are maximum inflation pressures.

PLEASE DO NOT USE THE ADVICE ABOVE TO SET YOUR TYRE PRESSURES!

MICHELIN TYRE PLC state in their "Tyre fitment and pressure guide (car 2006)" FOR GOOD HANDLING OF THE CAR AND TRAILER PACKAGE:

"Car fitted with MICHELIN radial tyres:
Increase the pressure in the rear tyres by 6psi(0.4 bar) when "cold", in relation to the normal inflation pressure for everyday use, unless the rear tyre pressure for "fully laden" or "speed" use is already more than 6psi (0.4 bar) higher. In this case, use the higher pressure.

Pressure in the caravan or trailer tyres:
If the manufacturer does not state recommended pressures, inflate to 3.0 bars cold"

3.0 bar is 43.5psi.

Contact the trailer or caravan manufacturer, or talk to experts at:
Michelin Technical Services Group on 01782 403258
www.michelin.co.uk

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I think that you will find that the information which I provided in my earlier post is correct, and I challenge either you or anyone else, to check it out on your/their particular 'van and then decide whether or not it is.

The max.tyre pressure stated on the sidewall of a tyre is the cold pressure required to support the tyre',s max. load, and could in fact equate to the tyre's running pressure, if, for example, on an agricultural trailer carrying machinery, when the tyre load could well be on it's limit.

Michelin's recommendation of 3.0 bar (43.5psi)on caravans/trailers is very misleading, not least because it doesn't take into account whether the caravan is single or double axle, or even tri-axle, as in the case of builders trailers.

My own caravan tyres have to be inflated to 65psi, and I certainly wouldn't be very happy heading off with them at 43.5psi.

I'm very much with you Eddie, how can one pressure fit all? the Michelin statement is out of context at the very least. Tyres have different constructions, how can a suitable pressure for a reinforced tyre be the same as a 6 or 8ply commercial, simply they ain't

But Eddie here (and I at other times) are not saying to use the maximum pressure, far from it Angu2you, that used to be the case before someone produced the equation in Eddie's post.

Deciding a pressure for a given weight is not a black art only known to a few, it's a simple calculation as long as you know the maximums for any given tyre and the actual load

>>Pressure in the caravan or trailer tyres:
If the manufacturer does not state recommended pressures, inflate to 3.0 bars cold"

3.0 bar is 43.5psi.

THE INFORMATION ABOVE IS INCORRECT AND POTENTIALY DANGEROUS.
( yes the blue writing )

On my old Sprite that would have ment i was running at 8.5psi over the max pressure , and on my new caravan it would mean being under pressure by 21psi .
I'd say it was dangerous to follow this general advice from Michelin ( they should know better ) , also i've never heard of a caravan manufacturer that makes a caravan and then doesn't state a tyre pressure for it ! .
Stick with Eddie's calculation and you shouldn't be to far away from the correct pressure .

atb

Wizard