I made a "motorhome-tire-pressure-calculator" in wich I use my own formula , wich is beter then that of the tire-makers, and adds first a reserve load for things like , pressure loss in time, unequall loading R/L, incidental extra loading or loadshifting during vacation, and whatever I might have forgotten to mention.
In case only GAWR's are given in part 1 it uses that with rear a reserve for overloading depending on the GVWR of the motorhome.
In case Weighed or assumed Axle loads are given in part 2, it uses those with a reserve of 10% added.
In case in part 3 4 point weighing is given it uses that and makes the weighed loads to be between 85% and 95% of the loadcapacity belonging to the adviced pressure.
All these used reserves are given to make it clear, but can be chanched by you , if you want it different, if you have other idea about it, so you stay boss.
It also gives more additional information wich can be usefull.
In this map on my public map of skydrive, take the newest american version ( so tire instead of tyre) and download it first by RIGHT-CLICKING
and choose DOWNLOAD
. Then open it in Excell or Open-office CALC on your computer . Dont leftclick or choose other because those are to complicated or cant handle some important things I used in most spreadsheets.
So in lack of weighing ( preferably 4 point) you can now look for the GAWR's ( mostly on same plate as pressure-advices) on car, and the tire-data as maximum load and pressure needed for that from the sidewalls.
If then questions pup-up or you want me to do it, ask me in this topic.