Here is my notes/data at two track days.
#1 Hot day, air temp mid 90sF, full sun, Afternoon, still air, Started session with 21F 23R, 10 laps/ 30 mins 24-25F 29-31R This track has a very fast long banked L and the higher pressure was in the RR. I didn't like the feel and will run 1-2 PSI less in the RR next time there.
#2 Cold day, air temp low 60's F, overcast, morning 30-35 MPH wind, Started session 23F 25R, 9 laps, 25 min, 25F, 27R.
Tires were SP8000 Dunlops 225.45.17 and 285.35.17 in both sessions above. I have since changed tires to 245.40.17 and 315.35.17 Sumotomos and used the same starting pressures. Have had similar results, about a 2-3 PSI gain to 25-26F 26-28R
Old rule of thumb divide the total vehicle weight by 100 and run that pressure in the tires all the way around as a starting pressure. Example, 2500 pound car / 100 = 25PSI. This isn't the BEST setup but it will be a safe starting point.
For a Sunday run down the highway at legal speeds/moderate temp day I would put 25-27 PSI in them and have a look at pressures in a couple of hours. Expect a gain of a pound or two. Much more that 30 PSI will result in a harsh ride and it's not necessary.
This is of course my car with my shock setting and spring rates and the way it feels to me. The fun of owning these cars is the learning. Try some stuff and get a feel for how things effect performance.