A solid tire comprising: a base rubber layer configured to be mounted on a sideringless rim being structured to include a rim seat and a flange portion, wherein the rim seat is structured to include a recess and a seat portion; and a tread rubber layer disposed outward of the base rubber layer in a tire radial direction, wherein a protrusion is disposed on an inner circumferential surface, in the tire radial direction, of the base rubber layer so as to protrude inwardly in the tire radial direction on one side in a tire axial direction, the base rubber layer includes a base inner circumferential layer forming the inner circumferential surface side portion including the protrusion and a contact portion, and a base outer circumferential layer disposed outward of the base inner circumferential layer in the tire radial direction, the base inner circumferential layer is formed of a first rubber material in which no fibers are blended, the base outer circumferential layer is formed of a second rubber material in which one or more fibers are blended, wherein the fiber has a diameter and a length, wherein the fiber length is not greater than 10 mm, wherein the inner circumferential surface, in the tire radial direction, of the solid tire is disposed on the rim seat when the solid tire is mounted on the rim, characterized in that the fiber diameter is not greater than 100 μm and wherein the contact portion is disposed on the other side in the tire axial direction relative to the protrusion and further comes into contact with the outer surface, in the tire radial direction, of the seat portion when mounted on the rim. a base rubber layer configured to be mounted on a sideringless rim being structured to include a rim seat and a flange portion, wherein the rim seat is structured to include a recess and a seat portion; and a tread rubber layer disposed outward of the base rubber layer in a tire radial direction, wherein a protrusion is disposed on an inner circumferential surface, in the tire radial direction, of the base rubber layer so as to protrude inwardly in the tire radial direction on one side in a tire axial direction, the base rubber layer includes a base inner circumferential layer forming the inner circumferential surface side portion including the protrusion and a contact portion, and a base outer circumferential layer disposed outward of the base inner circumferential layer in the tire radial direction, the base inner circumferential layer is formed of a first rubber material in which no fibers are blended, the base outer circumferential layer is formed of a second rubber material in which one or more fibers are blended, wherein the fiber has a diameter and a length, wherein the fiber length is not greater than 10 mm, wherein the inner circumferential surface, in the tire radial direction, of the solid tire is disposed on the rim seat when the solid tire is mounted on the rim, characterized in that the fiber diameter is not greater than 100 μm and wherein the contact portion is disposed on the other side in the tire axial direction relative to the protrusion and further comes into contact with the outer surface, in the tire radial direction, of the seat portion when mounted on the rim.