I am often asked what tire pressures should be for a particular Pirelli tire or a particular Goodyear tire, etc. The answer is, whatever the automaker designates as the correct pressure.
When a tire maker builds a tire of a certain size (i.e. 235/60R18) the tire could be installed on a number of different vehicles. But the automaker knows just how heavy a car is and the front-to-rear balance of that weight. This is why some cars utilize slightly higher pressure in the front or rear tires.
Automakers put their recommended tire pressure on the tire placard usually located on the driver's door jamb.