an anti - skid device is intended for use on pneumatic tires when the tires are used on ice and snow . the device includes a supporting disk with anti - skid arms pivotally displaceable about axes extending parallel to the axis of the wheel on which the pneumatic tire is mounted . the supporting disk is fixed to the wheel by a fixing disk and a retaining ring mounted on the wheel rim . the combination of the fixing disk and the retaining ring secure the supporting disk on a hub formed on the fixing disk . the supporting disk is arranged so that there is a certain amount of clearance relative to the hub for performing eccentric rotary movement for adapting the device to any elastic deformation of the pneumatic tire .