I have to (respectfully) disagree with some opinions here. I've changed a number of tires sticking to the same size on all of them and I've seen major differences in how much grip or wet performance tires had in the rain. Some tires would lock up easier on braking, while others would side-slip with little effort. The worst tires (for rain) I've had on my bikes were Schwalbe Duranos and so far the best -by far- have been Michelin Pilot (Protek Max) which perform excellent in the wet.