does tire siping help?
It alters the flexibility of the tread blocks and aids in wet and ice traction. In a performance application it is more of a hindrance than a help. In a bone stock car its fine, or in a car that is traction limited. Some people will tell you it hurts the tire or shortens its life, but this isnt 100% correct. It hurts the tire if you drive on gravel all day or drag race it (tire will chunk) but otherwise its okay. Because all tread blocks act as a heat sink to radiate generated heat, adding sipes increase the amount of heat rejection and the tire runs cooler. The technology has been around since the early 1900's and was originally done on leather soled shoes to keep them from being so slick.
pretty sure its most effective if the tire comes that way already...dont have any personal experience with it...try contacting a few different tire manufacturers for the best answer...but like stated by JB, it is for wet / snow / ice...not dry performance
i've had it done on some all season radials i had on another car and I can say it DOES cause the tire bits to chunk off. only small bits here and there though, like the corner of some tread blocks. very minor but wouldn't do it simply because they usually charge you like $10 a tire to do it.
