i see, i see

I usually stick to the same pressure all around. I also usually have the same tires all around. I've not gotten my suspension set up the way I want it yet, so I kinda figured finding that "perfect" pressure would be a mute issue. I have found out, from several different sources, that the suggested tire pressure on the side of most tires is the balance between comfort, life, and performance. You can actually increase that pressure quite a bit. Especially if you drive on rather smooth roads, like a prepped track. for a daily driven car, on normal city maintained roads, you have to temper your pressure with the bumps. Every time you hit a bump, it jacks the pressure in the tire way up. I've seen little hot shot kids blow their tires right off the rim hitting a bump because their pressure was at the same level as it was at the track.
A decent technique I've been told was to put shoe polish on the side walls of the tires. Run a lap. and check the shoe polish. If it has rubbed off, increase the pressure. If it hasn't, make a note of that, then back the pressure off a pound or two, and try it again. Its not perfect, but it gives a pretty decent +/- 2 or 3 psi range.