A pneumatic tire assembly includes a tire having a pneumatic cavity and a filter disposed between the pneumatic cavity and atmosphere. The filter is constructed of a hydrophobic material for avoiding all liquid adhesion. First and second sidewalls extend respectively from first and second tire bead regions to a tire tread region. The first sidewall has at least one bending region operatively bending when radially within a rolling tire footprint. A sidewall groove is defined by groove walls positioned within the bending region of the first tire sidewall. The sidewall groove deforms segment by segment between a non-deformed state and a deformed, constricted state in response to bending of the bending region of the first sidewall while radially within the rolling tire footprint.