I registered to this forum, to give info about tire pressure. 

Call myself ” pigheaded Dutch selfdeclared tyrepressure-specialist. 

End 2007 I got hold of the official european formula, to calculate it, and went running with it.

 

In the Netherlands, where I live, a motorhome is called a kampeerauto, but more often called Camper.

A travel-trailer, we call a caravan. 

But I know that in other country’s different names are used.

So, what is a runaway camper .

That is important to know , so what pressure-calculator I must use for you. 

Made multi-linguall calculator-spreadsheets, for mororhomes, and for travel-trailers.

In those I calculate with an even safer formula, then that official european, so leads to higher pressure. 

And first I add 10 or 11% to the given axle-load. 

11% adding is the same as making the given axleload 90% of the loadcapacity, belonging to the to calculate pressure. 

I call this 90% , load% , shortened L%.

I once determined by reactions, that if L% goes below 85% , that persons ( and animals) experiënce discomfort.

Below L% 80% , screws tremble loose from travel trailers. 

So my 90% average L%, makes a weightdifference R/L possible before one side trembles, and the heavy side goes over the overheating border. 

More reserve is created, because maxload of most tires ( exept ST) is given for 160kmph/99mph. 

And max speed for TT 75mpg, and motorhomes 87mph mayby. 

So my calculation is not the safe lowest pressure, but tge highest pressure,  at wich comfort and gripp is still acceptable..

But determining the real weights in your use, is the most tricky part in it all, and is your responcibility.