every car is different. on my camaro (275/40/17) i ran 21-22 psi. i'd start out around 25 psi. drive on that for a week or so & check your wear pattern. if it looks like it's wearing more on the corners, add a few psi. if it's wearing more in the center, take a few psi out. adjust the pressure & drive on them for another week. repeat until you can tell they're wearing evenly. for most cars, an even pattern will be in the 20-28 psi range. some people run more or less than that, but i've never seen one outside that range that had even wear.
track psi is a different story. you'll just have to adjust to whatever hooks the best. on the same 17s on my camaro, i ran 17 psi at the track.