Something I took for granted as general knowledge but today learned it is not.
If you fit tyres with non OEM size or ply rating then a rule of thumb is:
As the air chamber volume goes up, load capacity goes up.
As the pr goes up, load capacity goes up.
As load capacity goes up, tyre pressure probably best goes down equally.
Succinctly put: stiffer wall / more air volume = probably go down a bit on air pressure.
Same thing if your car carries more/less load = probably best go up/down in air pressure.
Same thing if you fit larger diameter rims = lower tyre = less air volume = probably go up in air pressure (bearing in mind the pr).
The air chamber thus the presure of it is súch an important part of the suspension. Please don´t overlook it.