A machine for fitting and removing the wheel tires of vehicles comprises a base frame with a turntable for gripping and rotating a rim of wheels for vehicles with at least a retention flange and a bead of a tire to be fitted on, or removed from, the rim; an operating head is operatively associated with the base frame, and is positionable near the retention flange. A stack of an MR element has a stacked structure comprising an underlayer, an antiferromagnetic layer, a ferromagnetic layer, a first nonmagnetic layer, a first soft magnetic layer, a second soft magnetic layer, a second nonmagnetic layer and a high-resistance layer, which are stacked in sequence on the underlayer. 1% by weight of the rubber of volatile organic compounds, especially alcohol, during compounding and further processing.