I set mine by looking at the wear on the edge of the tread (tires roll over in turns). If I ran 32 PSI in the frt I would wear out the outside edge in 20k miles. I got 58k miles out of a set of GY Eagles and I was not nice to them either. If you corner faster than normal folks, you may need more PSI in your tires if you want them to last. The ride is a little more harsh but I can live with it.
I tried to check the pressure regularly so they're all even. I had one of my tires go down pretty low once and it's amazing how out of alignment (track to the left or right) your car can get.