Factory Specs on Tire Pressure?

I also go by whats on the side of the tire. I wasn't aware that different
types of tires call for different max pressures.

You learn something everyday. I have some tires that have a 51 psi max
and others that say 35 psi

I keep them 5 t0 8 lbs less than the max. I'm sure the pressure
increases as the tires warm up.