Here is something on calculating coefficient, just find the 2nd reply
http://www.chiefdelphi.com/forums/sh...ht=coefficient
Edit:Sanddrag beat me to posting so no need for the link.
From experience though, the IFI Traction Treads, roughtop/wedgetop are the way to go if you want traction. IFI did some math and found out Wedgetop has a coefficient of friction of 1.2 and the roughtop has a coefficient of friction of 1.3.