Fluid dispensing apparatus for a tire wheel assembly having a wheel supported ring member with a diameter greater than the wheel rim diameter and less than the tire tread diameter. A fluid chamber is provided radially inward of the ring and an opening in the ring accommodates a passage leading from the fluid chamber to the radially outer surface of the ring. A closure for the passage extends radially outward from the surface of the ring for opening upon engagement by the tire during deflation and for dispensing fluid from the fluid chamber through the passage to the radially outer surface of the ring. The closure may be of a flexible material to withstand impact loads without rupturing during operation with the tire in an inflated condition but having a limited tear strength to rupture and release fluid under circumferential shearing forces during operation with a deflated tire.