Here, here on your comment.
However on to the real thing.
If you look at the side wall of the tyres you will eventually find A comment like 520Kgs max load at 36psi or some thing like that.
It is what is known in the trade as the casing limit. So long as you do not go above that pressure then your tyres will be safe until you can get a recomended pressure from the manufacturer of your caravan.
I use the csing limit for my van as the manufacturer has long since dissapeared and as there were only 20 or so made, I doubt if I could get any help with "constructive advice". I have not yet had any problems andthe van tows fine.