I know I have answered this question in the past but maybe it was on an RV forum for a single-brand RV so not everyone has heard this. So here goes.
Many, but not all, tires have the words "Max PSI" followed by a number on the tire sidewall. I have no idea which lawyer wrote the requirement but he or she didn't understand how those words would be misinterpreted.
Too often I see people saying that the tire should never be run with a higher pressure or that this is the absolute only correct pressure for the tire, but these assumptions are incorrect.
I hope everyone reading this post understands that tire load capacity is related directly to tire inflation and if they want to increase the load capacity they will need to increase the inflation. While it is true that an increase in tire inflation is required if you want more load capacity, there is a limit. The limit is controlled by industry standards which are published and followed by all tire companies.
Each tire has a Maximum Load Capacity and to get to that capacity you need to increase the tire inflation BUT there is a limit as each tire also has a limit or maximum load capacity and increasing the inflation above the stated pressure WILL NOT increase the load capacity.
So you have a tire that says "Max Psi 65 psi" which means you will gain increased load capacity as you increase inflation from 35 to 45 to 60 and to 65 psi BUT any additional pressure above 65 psi WILL NOT RESULT in any additional increase in load capacity.
It is also important to know that tires are tested and can tolerate higher pressures due to being warmed up by running so the pressure on the tire sidewall only refers to the tire "cold" inflation so you should not bleed down the hot pressure.
Have a tire question? Ask Roger on his RV Tires Forum here. It's hosted by RVtravel.com and moderated by Roger. He'll be happy to help you.