A buoyant vehicle tire device for facilitating driving in muddy soil includes a tire having an exterior wall and a pair of side walls is attached to each one of a pair of side edges of the exterior wall. A vehicle rim is sealed against the end edge of each side wall and encloses a pressurized space between the side walls and the exterior wall of the tire and the vehicle rim. A valve is coupled to the vehicle rim and is in fluid communication with the pressurized space. A plurality of depressions is positioned on the exterior wall and is pushed out from a first position to a second position when the pressurized space receives additional air. The first position of each of the depressions has a container space receiving air when driving in muddy soil, wherein the depressions provide buoyancy to the tire in muddy soil.

A stud unit (3) and a device (1) for a studded tire. The stud unit comprises a housing (5) with a chamber (7) enclosing a medium, a stud (20) arranged at least partly inserted into the chamber so that it is affected by the medium. The stud is adapted to be moved depending on a change of the pressure of the medium in the chamber between a first position for a first pressure and a second position, where the second pressure is higher than the first pressure. In the second position a part of the stud protrudes further from the chamber than in the first position, The stud unit also contains a heating element (22) adapted to heat the medium so that the pressure in the chamber is adjusted between the first pressure and the second pressure.

A tyre T for adaptively adjusting to the tyre's rolling conditions, the tyre T comprising first and second side walls (1, 2) with a contact wall (3) extending therebetween and a heater 7 for heating one or more of the first side wall (1), second side wall (2) and contact wall (3), wherein plural chambers (4, 5, 6) are defined within the tyre T, at least one of the plural chambers (4, 6) being selectively inflatable for altering the external shape of the first side wall (1), second side wall (2) and/or contact wall (3).