A tire monitoring device includes a housing mounted within a cavity of a tire/wheel assembly. A sensor within the housing senses a condition within the cavity via an open passage in the housing. A hollow first tube extends away from the housing coaxial to an axis of the open passage. The first tube has an internal bore aligned with the open passage, and includes: a first tubular portion having a first cross sectional width; and a second tubular portion having a second cross sectional width smaller than the first cross sectional width. The second tubular portion further has a free end opening positioned in the cavity above a level of a liquid present in the cavity when the tire monitoring device is positioned at a lowest point in the cavity. The opening has a cross sectional width sized to prevent entrance of the liquid past the opening.