PURPOSE: To prevent a tire from chaps in the molding of grooves by providing the tire molded with special grooves such that it can travel on a road frozen with snow, ice storm or the like without scraping off the road surface and slipping thereon.

CONSTITUTION: A metal pin shaft 2 is inserted between bifurcated pieces formed by doubling a metal sheet 1 on the inner bottom of the formed bend and both pieces are moved into intimate contact with each other by pressing the bifurcated pieces from the outside surfaces. The boundary between the formed bend having the pin shaft inserted and the bifurcated pieces is formed smoothly without angular portions, and the bifurcated pieces making intimate contact with each other are welded 3 to each other near the edge sides. After the bifurcated pieces are drilled if necessary at predetermined spots, the whole outer surfaces is polished.