"wet" seems to always refer to water that can be channelled through the grooves of the tire; hence a tires "resistance to hydroplaning" depends a lot on the tread design.

What happens to tire traction in the "damp"; where there is not enough water on the road to be channeled by the tread? Is damp traction more or less than dry traction (in a general sense)? More info?

I'm not talking about "just beginning to sprinkle rain" stuff as there are too many road variables. I'm referring to a controlled environment comparing a dry surface to the same surface that was wetted down and is damp, but has no standing water.

Actually slightly damp roads can be the slipperiest. When the road is dry oil and dirt build up in the road surface. When it first starts raining, or the road gets wet somehow, all the oil and dirt lifts to the top and makes an oil slick. After a while all the oil washes away and you're left with just water and pavement.

I suspect stickier tires would handle damp roads better than harder tires.

Double :banana:

Wet/damp traction will always be worse than dry traction. How much of a difference depends heavily on the tire.