I got my tires siped a couple of months ago too as they had become a slick as glass in the Detroit snow and ice storms. My 3 year old Yokohamas still have more than half the tread left after 40,000 miles and were really expensive and I couldn't find the Nitto Terragrapplers that I wanted for the winter so I decided to try the siping and I think it worked. Discount tires did it for $40 and I slip a LOT less. They say it makes the tires last longer and ride smoother as they are more flexible and thus don't heat up as much I guess. The only drawbacks that I see are your tires look a little funny as there are millions of little exacto cuts across the treads basically.... not like molded-in sipes at all, and the tires make an almost turbocharger like whistle now. But they're not too obvious or anything and sound kinda cool actually and if they keep me from crashing they're OK in my book!