Siping, putting slits in the tread blocks, was done years ago to bias ply snow tires to improve traction on ice. It basically allows each block to squirm more, putting more edges on the ice. Today’s tire technology allows tires to come out of the mold already siped. In addition to being unnecessary, siping on a modern radial tire can decrease the life of the tire and can cause premature tire failure do to heat buildup from the aforementioned “squirming” of the rubber.
Do not do this.