must previously have been detached excepting the plate and nut at the base of the stem. Before replacing the tube, see

Fig. 10 that the overlap at the join is facing towards the back of the car, and not forwards. Then push the stem through the rim, meanwhile holding up the cover as in fig. 10. Place the rubber washer and large nut on the stem, but do not screw right home. The tube should then be passed round the bed of the rim, without any twist, and without being slack at one point and stretched at another.

Now insert the remaining parts of the valve, except the cap, and inflate slightly, just sufficiently to make the air-chamber round, but without the least stretching of the rubber. Then pass the hand all round, between the tube and cover, to make sure that no creases remain.

To Replace the Cover. Unscrew the rim nuts sufficiently to allow the valve to be pushed upwards, and the beaded edge to pass into its place. Force as much of the cover into

position as is possible by pressure from the hands, and then insert the lever as in fig. 11, and by lateral oscillation work the remainder into the hook of the rim. If the cover assumes the position seen in fig. 12 replacement will be difficult. In that case fix the lever with a single prong in the position shown in fig 13, and depress the other lever. Then bring the levers towards each other, and push the cover along the