The rating on the tire is usually "Max Cold Pressure" the tire manufacturer allows. I normally run 90% of that such as 44psi max cold pressure listed on the OEM tires on the FJ, I run about 40 psi.
Now for certain vehicles there may be a difference between front and rear dictated by design. I may be dating myself here but I owned a few Corvairs (rear engine-rear drive) and they needed a 10 psi difference front to rear because of weight bias, more pressure in the rear. I imagine front wheel drive vehicles would be similar.