hydroplaning (long-ish)

[tihol tiholov]

Huw sez:
>Think of what happens when you hit a puddle, say, at least 1/2" deep -
no matter what the tire is, if you're going fast enough it simply rides
on top of the water.

A-ha - driving on "wet" or "rain"-type tire "fast enough" for
hydroplaning is faster (higher speed) than with a "slick" to compare
exteremes.  Slick starts "riding on top of the water" at a lower speed -
poor water expelling.  Wet tread pattern allows the same car to go
faster on wet roads than with dry tires.  Same for new (deeper grooves)
and old tires.  If tread pattern didn't matter car maintenance would be
a lot cheaper and tire-makers a lot poorer.  And I'd buy tires at
Canadian tire - yeah, right ;o)  
You gyus never seen the huge amount of tires brought to the car races?  
 
Even the patch 'n' pressure theory is limited and assumes the tire to be
a barely-flexible car support.   In rally there are at least 3 degrees
of tire softness, in racing (e.g., F1) - at least 4.  These tires leave
different size patches for the same car weight, pressure, etc.  This
year even the governing bodies ask WRC and F1 teams to anounce which
tires they'll run a few days or weeks in advance relegating classic
gambling to a kid's play.  Recently Carlos sainz very likely lost a
rally win because he had to use the same set of tires for another 70 km.
 Tell that guy at the time that tread didn't matter and see if Nomex
saves your skin ;o)
Maybe it matters less in NACAR ;o)
Yeall keep ridin' on nahce tires naow   

TT