Abstract: A variable diameter wheel comprises a central hub, a peripheral band formed by a plurality of arcuate segments, each one of the arcuate segments being linked to the hub, wherein the hub comprises radial guide means for sliding retractable radial arms, each one of the retractable radial arms being secured to the distal end thereof of one of the arcuate segments, the opposing end being provided with a connection member with a mobile plate coaxial with the hub and in relative rotation with respect to the hub, the mobile plate having curved guide areas, each one of the connection members cooperating with one of the arms in order to control the linear and radial movement of the proximal end of the corresponding arm.