for snow and ice driving on roads you want Siping. If you tires are used, some tire shops will sipe them and some won't. Lots of places will only sipe new tires. A shop should charge between 7 and 15 bucks per tire to do it, and yes... it does help alot on slick roads. As for doing it yourself, it would take you forever to put enough slits in them w/ a razor knife to make a difference.