Posted by Rick on November 03, 1999 at 11:02:30:
In Reply to: Re: Re: tread pattern on high perfomance tires ? good or bad ? posted by ken on October 30, 1999 at 14:11:49:
It is surprising to see a hydroplanning photograph. You will see water is splashed from the leading edge. However, water is also "pumped" out of the front of any grooves. The idea is that the more water that builds up on the leading edge the sooner the tire will hydroplane. Now water does also pass through the grooves as well. The idea behind angled grooves and slots is that this water is directed not only through the slots but that it shoots the water away from the leading edge.
I have seen a couple of TV ad's that have hydroplanning photos on them. If they have not been touched by the marketing people the faster the claimed speed the smaller the contact patch. At .05" of water most tires have very little contact area (or none) at 55 mph. The next time that you are in the passenger side of a car watch the car (or a truck is better) next to you to see how much water is splashed back in front of the car.
Note that the above paragraphs mentioned only hydroplanning. There are lots of other criteria for wet performance. You also want a good match between the block stiffness and the stiffness of the compound. The compound grip and block stiffness work together to generate the wet handling.