Signed in to this forum, to go worldwide with mij articles about calculating tire pressure.

I am from Holland so exuse me for mis-spellings and poor Englisch.

On the dutch camperforum the question of tire-pressure was asked often, but now not anymore.

I have got hold of a copy of the first page of the European Tire&Rim Technical Organisation 2007 standard manual.

On that page some formula's witch the big tire-facturies use to calculate the correct tire pressure, for normal car tires on the road.

I have simpliefied them to 1 formula wich normal people can use.

Under the next link you can find the car version and ideas for re-calculating when you have tires with chanched specifications.

http://board.carstyling.net/showthread.php?t=67492
Sorry, it is in Dutch so someone has to translate. Luckily the formula stays the same.

So here it is so you can work with it .

A=B*(C/D)^1.25

A= the tire pressure you want to know

B= the maximum tire pressure,which you can find on the tire

C= The actual weight on the tire, the most discussable item.

D= the maximum load for the tire, also can be found on the tire in lbs, kg, or Load-Index( search in list on internet for the maxload then).

The minimum is 1,5 bar =??psi but I have seen in lists for car-tire pressure that 1,4 as minimum is also used.

And mind that there are 2 (somethimes 4) wheels on an ax .

To calculate what weight the tire can bear at a certain pressure you can use the next formula.

C=D*(A/B)^0,8

A= the actual pressure on the tire

B=same as above

C= The load the tire can bare at the actual pressure

D = same as above.

2^2 meens 2 square 2 = 4 on mathematical calculators, also that of windows calculator jou can find a button X^y.

Mayby there is someone on this forum with mathematical interest , who can work it out . You can send me a personal message for more information or place it under this topic. Mind that you have to build in a savety-factor. When you add 10% to the weight on the tire for calculating , the car stil rides comfortabel.

I am also prepared to give some examples here, give me the right information and I wil give you a full report.

Mind that ,though the tire-firm used the sises of the tire and some more data to determine the max weigh, the sises are not needed for calculating. Only Load index and maximum Pressure are needed from the tire, and can, almost always, be found somewhere on the tire.

greatings from Peter