Question: what function do sipes perform?
Answer: Siping is a process of cutting thin slits across a rubber surface to improve traction in wet or icy conditions. Siping was invented and patented in 1923 under the name of John F. Sipe. The story told on various websites is that, in the 1920s, Sipe worked in a slaughterhouse and grew tired of slipping on the wet floors.