A wheel includes a primary ring having a stepped core part and a tire formed of a urethane material as an outer surface thereof, and an auxiliary ring provided on a circumferentially-central portion of the primary ring, on which the tire is provided, in an insertion manner. The primary ring is formed of a plastic material, and the auxiliary ring is formed of a metallic material that is different from the material of the primary ring.

A hub or wheel assembly includes a retaining element, biasing element, and hand-maneuverable release mechanism. The housing includes an axle bore configured to receive an axle and a pin sleeve including a first end in fluid communication with the axle bore, a second end, and a conduit between the first end and the second end. The retaining element is within the conduit and is configured to operatively engage a groove in an axle. The biasing element is within the conduit and is configured to bias the retaining element towards the axle bore. The hand-maneuverable release mechanism is configured to displace the retaining element away from the axle bore.