Specially conceived for vehicles which have to be displaced over ferromagnetic surfaces, like the iron or steel walls of large tanks for example, it is incorporated by the combination of a hollow rim (1 1') and a tyre (4) of an elastomer or similar material, which define a cylindrical chamber (8) inside which a magnetic annulus (9) runs, materialized in a permanent magnet of adequate strength, with the particularity that said magnetic annulus (9) has a substantially smaller diameter than that of the cited chamber (8), so that it is capable of carrying out a planetary motion inside the same, maintaining a permanently tangential condition with the tyre (4) at the point in which the latter is in contact at all times with the ferromagnetic surface over which the vehicle is displaced, achieving maximum adherence at said point. In this way it is managed to improve the grip of the wheel on said surface, overcome possible obstacles of the same, lighten the wheel and increase safety through not requiring an electricity supply.