As I've pointed out before, I also agree that there is some fundamental fault with the tire pressures. After reading all this, more experimenting and more thinking, here's my current take on it:
It makes sense to me that running pressures lower than ideal has one major drawback: temperature build-up due to excessive tire deformation (particle "rubbing").(Let's ignore "ridiculously low" pressures for now, that has one major drawback being the failure of the tire, and that is best fixed by adding a script into the existing model imo, or just plain blocked from using such pressures as most sims do).
Now this in and of itself is, I think, not a big enough downside to kill the gain from the increased contact patch, IF you can keep the temperatures in control. Here's where rf2 really differs from other sims: running pressures too low doesn't overheat the tires. And I have an idea on why, based on another known fault with rf2: asphalt temperature has absolutely no effect on tire temperatures or pressures.(I've taken this for granted for years,I might be wrong, let me know if this is the case).
You can see this in other sims. I remember for example in AC I had a race in nurburgring, and practiced for it with the default settings, which would be something around 25c track temperature. Then come race day, and the server was running real weather, which meant the asphalt was a chilly 3°c since it was a cold day there (surprise, lol). This meant I HAD to lower pressures - to the minimum nonetheless-to keep temperature on the tires, BUT it also meant that once the tires started working I had a lot more grip to work with.
This fits with what I believe is wrong : the reason I believe you have to run higher pressures on hotter asphalt is because of the lower heat delta between tire and road* causing lower thermal transfer/cooling of the tire, which means heat build up. Since this has no effect in rf2, its like driving on chilly tarmac the whole time, so the tire never overheats.
Thoughts?