Abstract: A roller includes a rim assembly and a tire assembly. The tire assembly includes a support ring and a tire mounted at the periphery of the support ring. The support ring and the rim assembly are detachably connected by a buckle structure. The buckle structure includes a plurality of elastic accommodating parts disposed on the inner side of the supporting ring, and a plurality of buckling parts disposed at the rim assembly. The elastic accommodating parts and the buckling parts are detachably connected. The elastic accommodating parts protrude out of the inner side of the support ring, and two ends of each elastic accommodating part are separately provided with a protruding first limiting block and a protruding second limiting block. The buckling parts are limited by the first limiting blocks and the second limiting blocks. The rim assembly and the tire assembly of the roller are detachably connected.

Abstract: A wheel assembly including a rigid wheel having a radially outer rim wall presenting a polygonal shape with a plurality of outermost vertices connecting a plurality of planar faces, and a flexible tire mounted on the outer rim wall. The planar faces of the rigid wheel each have a spacer positioned thereon. The tire is supported by the vertices of the rim wall and is separated from the rim faces by a space, portions of the tire located between the vertices being configured to flex inwardly when subject to ground engaging pressure, the spacers configured to limit the amount of inward flex of the portions of the tire between the vertices.

Abstract: A tire includes a plurality of helical springs. Each helical spring includes a first end portion, a second end portion, and an arching middle portion. Each helical spring is interlaced with at least one other helical spring thereby forming a laced toroidal structure extending about an entire circumference of the tire.

Abstract: A wheel has a plurality of variable length spokes extending radially from the hub to the rim and supporting the rim coaxially around the hub. Spoke length varying devices vary the lengths of the spokes.