Abstract: A device for automatically maintaining tire pressure is adapted to pump air into a tire up to two times per wheel revolution. Embodiments of the device include a flexible compression strip adapted for attachment to an inner peripheral surface of a tire. Opposing compression faces on the compression strip apply pressure to a compression tube attached to the compression strip. Air in an air reservoir inside the compression tube is expelled from a collapsible segment of the compression tube pressed on by the compression faces and into accumulator segments extending beyond the edges of the compression strip. A ratio of the combined volumes of the collapsible and accumulator segments to the volume of the collapsible segment determines a set point pressure. Air is expelled into a tire having an inflation pressure less than the set point pressure but is not expelled into a tire having pressure greater than the set point pressure.