The ornamental design for an airtube for pneumaticbicycle tires, as shown and described.
FIG. 1 is a perspective view of an air tube for pneumatic bicycle tires incorporating our new design, it being understood that the exterior pattern repeats circumferentially throughout the outer circumference; and,
FIG. 2 is an elevational view of one side of the design as shown in FIG. 1.
In the drawings, the broken line showing of a valve stem depicts environmental subject matter and forms no part of the claim.