An air chuck configured to facilitate the connection of a pneumatic hose with a threaded stem of a tyre valve, the air chuck comprising; an elongate housing defining an air passage through the full length thereof, a rear end of the elongate housing including an air inlet port configured to connect to the pneumatic hose, and a front section of the housing comprising an air outlet passage, a discharge end of which is configured to receive the threaded stem of the tyre valve; and a clamping member, mounted externally about the outlet passage, characterised in that the clamping member comprises a hollow tubular member, at least a front end portion of which terminates in a plurality of separate, radially deflectable fingers, a free end portion of each finger extending towards the discharge end of the outlet passage, the combined free end portions of each finger together defining an aperture configured to receive the threaded stem of the tyre valve, and one or more engaging formations are located on an internal face of each finger towards the free end portion, and the size of the aperture is variable by the movement of a sleeve member, slidable over the body of the elongate housing and the clamping member, between a first position in which the fingers are compressed inwards to minimise the size of the aperture for engagement of the one or more engaging formations with the threaded stem of the tyre valve, and a second position in which the fingers are released to deflect outwards, and the size of the aperture is increased to release the threaded stem of the tyre valve from engagement with the one or more engaging formations, wherein the sleeve member is biased in the first position by a first biasing spring, and connected by a linkage mechanism to a trigger which is pivotally mounted on the elongate housing and activatable to draw the sleeve member from its first position, over the elongate housing against the bias of the biasing spring, to its second position; the inherent bias of the first biasing spring biasing the sleeve member from the second position back to the first position, on release of the trigger. an elongate housing defining an air passage through the full length thereof, a rear end of the elongate housing including an air inlet port configured to connect to the pneumatic hose, and a front section of the housing comprising an air outlet passage, a discharge end of which is configured to receive the threaded stem of the tyre valve; and a clamping member, mounted externally about the outlet passage, characterised in that the clamping member comprises a hollow tubular member, at least a front end portion of which terminates in a plurality of separate, radially deflectable fingers, a free end portion of each finger extending towards the discharge end of the outlet passage, the combined free end portions of each finger together defining an aperture configured to receive the threaded stem of the tyre valve, and one or more engaging formations are located on an internal face of each finger towards the free end portion, and the size of the aperture is variable by the movement of a sleeve member, slidable over the body of the elongate housing and the clamping member, between a first position in which the fingers are compressed inwards to minimise the size of the aperture for engagement of the one or more engaging formations with the threaded stem of the tyre valve, and a second position in which the fingers are released to deflect outwards, and the size of the aperture is increased to release the threaded stem of the tyre valve from engagement with the one or more engaging formations, wherein the sleeve member is biased in the first position by a first biasing spring, and connected by a linkage mechanism to a trigger which is pivotally mounted on the elongate housing and activatable to draw the sleeve member from its first position, over the elongate housing against the bias of the biasing spring, to its second position; the inherent bias of the first biasing spring biasing the sleeve member from the second position back to the first position, on release of the trigger.