A tire mold and a molding device for forming a sunken groove in a tire are provided. The molding device includes one or more rigid elements joined to a flexible member. The flexible member is formed from a flexible material, preferably a superalloy, or hyperelastic material. The molding device may further comprise a magnet. A portion of the flexible member is positioned in contact with a first surface of a relief forming element of a mold and the rigid element has a mating surface in mating contact with a second surface of the relief forming element. The mold further may further comprise a second relief forming element positioned adjacent the first relief forming element, wherein the rigid element further includes an outer surface in mating contact with a surface of said second relief forming element.