What are Sipes in a tire?

Sipes are the small slots that are cut or molded into a tire tread surface.  These slots are meant to aid in increasing traction in snow, ice, mud, and wet road surfaces.  The name of the concept of siping a tire comes from a man named John Sipe, who received a patent in the 1920’s, after realizing that an array of small transverse cuts in the heels of his shoes gave him better traction. Later Goodyear received a US patent claiming that the “sipes” improved traction characteristics in tires.

Tire tread is a series of block shapes, groove configurations, and sipes, all of which have an affect on the tires traction and noise level.  Typically, wide, straight grooves running in the direction that the tire travels will have a lower noise level and good water removal. More lateral grooves running from side to side will usually increase traction while increasing noise levels. Sipes are the small grooves or slits that are cut across larger tread elements. Up to a point, more sipes give more traction in snow and mud as well as over various terrains found offroad.