Originally Posted by merlinextraligh

Not an engineer but that makes Zero sense to me. The available grip is a function of the coefficient of friction of the material on the road surface, and the size of the contact patch. More pressure = smaller contact patch = less grip.

At best, you might be able to argue that high end tires such as the Michelin Pro Grip for example (compared to Pro Race) have a higher coefficient of friction because of softer tread compound, and therefore you can still have good grip at a higher pressure.

The reason people lower pressure racing in the rain is to increase the contact patch size and increase the grip.