As The Rad King mentioned, the correct tire pressure needs to achieve two different goals at the same time: proper inflation (even pressure across the width of the tire/proper roll in corners) along with optimizing tire temperatures.
The best way to get the inflation pressure correct is to use the sidewall markers (little triangles) to detect how far the tire is rolling over in corners. Decrease pressure if wear is not close to the markers (to let the tire rollover more) or increase pressure if wear is past the markers (to stiffen the tire and reduce rollover).
Then use a pyrometer to measure tire temps and adjust pressure as needed to get the tire temp to the optimal temp range.
Here is a good tutorial:
Using a tire pyrometer-949 Racing
Here is an example of my tire temps from a testing day. We took three measurements across the width of the tire for each tire: