What you need:
- An Accu-gage or similar swinging needle gauge.
- A clip-on tire chuck.
- Male quick disconnect coupler.
- Three 1/4" threaded pipe nipples.
- A tee fitting for 1/4" pipe.
- A 1 foot long 1/4" rubber hose, Gas line hose or vacuum hose works fine.
Remove the valve fitting from the gauge. It screws in to the bottom of the gauge. Replace with a 1/4" nipple. Attach the Tee fitting to the other end of the nipple. Opposite the gauge on the tee attach another 1/4" nipple. Slip the hose over this nipple. Hose clamps are not necessary as long as the hose doesn't fall off. At the other end of the hose add the last 1/4" nipple and the tire chuck.
To air down the tire attach the chuck to the valve stem. The air will escape through the open side of the Tee. To check the pressure remaining close the hole in the tee with a finger or thumb and read the pressure on the gauge.