A locomotion assembly (200; 300; 400) for a land vehicle, the locomotion assembly (200; 300; 400) comprising: a flexible, elastomeric ground-engaging member (202; 302) having wheel-like, essentially circular configuration with a ground-engaging surface (204, 304) with first and second rims (206, 208; 306, 308) corresponding to first and second sides (210, 212; 310, 312) of the locomotion assembly (200; 300), and a pair of frustum-conical members (216, 218; 316, 318) integrally formed with said ground-engaging member (202; 302), each of the frustum-conical members of the pair extending between its relatively narrow (222, 224; 322, 324) and its relatively wide end along a common frustum-conical axis and being rotatable about said axis, each of the frustum-conical members of the pair comprising a plurality of rigid spikes (230; 330) defining together a mid-portion of the frustum-conical member linking between first and second end portions (226, 326; 228, 328) thereof and being received in slits defined in the first and second portions, thereby forming a grid enabling engagement between the frustum-conical members of said pair; the frustum-conical members of the pair being symmetrically oriented and jointly supporting said ground-engaging member at their wide ends, thereby defining first and second circular, substantially V-shaped, grooves (232, 234; 332, 334) in respectively the first and second sides (210, 212; 310, 312) of the locomotion assembly (200; 300), each of the V-shaped grooves being defined by a first, more peripheral wall (226; 326) and a second, more central wall (228; 328) of the respective side of the locomotion assembly, said first and second walls of the groove being formed by surfaces of the first and second frustum-conical members of the pair (216, 218; 316, 318), said first and second V-shaped grooves being therefore arranged with opposite symmetric orientation, providing radial compression of the locomotion assembly by reversible deformation of the first and second grooves, thereby permitting reversible deformation of the ground-engaging member (202; 302) from a substantially circular shape to a deformed shape in which a larger portion of the ground-engaging surface is in contact with a movement surface. a flexible, elastomeric ground-engaging member (202; 302) having wheel-like, essentially circular configuration with a ground-engaging surface (204, 304) with first and second rims (206, 208; 306, 308) corresponding to first and second sides (210, 212; 310, 312) of the locomotion assembly (200; 300), and a pair of frustum-conical members (216, 218; 316, 318) integrally formed with said ground-engaging member (202; 302), each of the frustum-conical members of the pair extending between its relatively narrow (222, 224; 322, 324) and its relatively wide end along a common frustum-conical axis and being rotatable about said axis, each of the frustum-conical members of the pair comprising a plurality of rigid spikes (230; 330) defining together a mid-portion of the frustum-conical member linking between first and second end portions (226, 326; 228, 328) thereof and being received in slits defined in the first and second portions, thereby forming a grid enabling engagement between the frustum-conical members of said pair; the frustum-conical members of the pair being symmetrically oriented and jointly supporting said ground-engaging member at their wide ends, thereby defining first and second circular, substantially V-shaped, grooves (232, 234; 332, 334) in respectively the first and second sides (210, 212; 310, 312) of the locomotion assembly (200; 300), each of the V-shaped grooves being defined by a first, more peripheral wall (226; 326) and a second, more central wall (228; 328) of the respective side of the locomotion assembly, said first and second walls of the groove being formed by surfaces of the first and second frustum-conical members of the pair (216, 218; 316, 318), said first and second V-shaped grooves being therefore arranged with opposite symmetric orientation, providing radial compression of the locomotion assembly by reversible deformation of the first and second grooves, thereby permitting reversible deformation of the ground-engaging member (202; 302) from a substantially circular shape to a deformed shape in which a larger portion of the ground-engaging surface is in contact with a movement surface.