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ZDan cool that you are into nerdy bits as well then! When I was talking about pressures, I always meant hot pressures, cold pressures are mostly irrelevant as just as you say, the rise on pressure while out there on the track depends greatly on ambient temperature as well. Some days I need to go out at 22psi, some days I need to go out at 26-28psi to get in the same 30-32psi range, which is also why I usually need several sessions.
For tire temps, I dont take them hot in pits without a cooldown lap, because it will tell you exactly what you are implying, surface temperature. My cooldown laps are fast enough to keep some heat on tires, but slow enough that I dont have to touch the brakes (mostly, sometimes traffic gets in the way), Im only trying to cool the brakes (and a bit the engine too, so I keep rpms low).
So my observations after taking temps after this kind of cooldown are that temps rise or stay about the same a bit after pitting, and then start to go down, but relatively slowly. 2-3 minutes after pitting, its still within 5-10F of their temp after I pitted (I do try to go deep with that needle point, but obviously its still only a couple of mms of penetration).
So anyways, I dont know exactly why I got the temperatures I do, but as an example, two events ago I was at a track where I was overheating the tires (temps were in the 220-240F range after pitting), for the next session I dropped the pressure by 4 psi (32 to 28, it was on nankang AR1s, their website even recommend very low pressures) and after doing a similar session my temps were in the 170-180F range. Could I have been avoiding overheating the tire after knowing in advance that they were overheated? Probably. I went faster, so I wasnt driving slower, maybe tidier? The temperature on my datalogger says 1C higher temp on that session, so if anything tires should have been hotter. Later that day, in the afternoon, the temps dropped quite a bit, and so did my pressures, I noticed the tire started rolling over so I pitted and measured temp and pressure, it was in the 25-26PSI range and temps only up to 140F. I pumped the pressure back to 30PSI hot for the next session and after it when I measured temps I was at 170-190F.
I dont fully understand those measurements. I mean, I can see the pattern, but I dont understand why it does what it does. If you or anyone wants to illuminate me on that, I would greatly appretiate it.
As a side note, I do a lot of sim racing to keep in shape during the winter. On sims (Assetto Corsa and Iracing), higher pressures = higher temperatures on the tires. They are, of course, cold pressures as you cannot really set hot pressures, but higher cold pressures end up being higher hot pressures, not relly rocket science there. So there has to be something there that can be somewhat easily explained.