Tire pressure question

Tire dimensions are spec'd on a certain rim width.
There are differences in the load capacity of Metric, P metric, Alpha Numeric, LT sizing of tires.
P-Metric Tire Load and Inflation Table - TirePressure.com
What is a Hard Metric Tire? Critical Tire Buying Tips | DrivingLine
Tire Width for a Wheel/Rim Size Chart
Never use less pressure than the tire sticker on the drivers door jam. It gives the proper size and type of tire recommended for that vehicle.