Tyre Deflators

TRAILHEAD Automatic Tyre Deflators will automatically reduce the air pressure in a tyre to a predetermined level and stop, preventing any further loss of air from the tyre. They will function properly whether your vehicle is stationery or traveling at speeds of around 30km per hour or less.

Trailhead Automatic Tyre Deflators

The shut off pressure on your tyres may vary due to several factors, especially the flow rate of your valve stems.


1. Turn adjusting screw with a 5/32” allen wrench counter clockwise until it is even with the end of the body tube. This will set pressure at the lowest end of the adjustment range. Every complete turn clockwise will increase pressure approximately 1.5psi for the 5-20psi
range, and 3psi for the 15-40psi range.

2. Turn the adjustment screw clockwise the desired number of turns and follow “OPERATING INSTRUCTIONS”.

3. If tyres have not deflated to the proper value, make minor adjustments to the adjustment screw, re-inflate and re-test. Some experimentation may be necessary to find the exact setpoint. This process goes quickly if a small spare tire (i.e. wheel barrow tyre, ATV tyre, etc.) is for use during the adjustment process. This process should take about 15 minutes as opposed to over an hour using a full size off road tyre.

NOTE: In order for deflators to reliably begin operation, tyres must be inflated to a pressure approximately twice the setpoint, e.g. If the deflators are set to shut off at 10 psi, tyres must be inflated to approximately 20 psi or greater.

1. Remove valve caps and replace with one tyre deflator on each tyre.
2. Wait until deflators are finished deflating and remove them from the valve stems.
3. Check pressure and make any adjustments to tyre pressure or deflators setpoint as necessary.

Consistency is more important than accuracy. Usually it is more important to have both tyres on a given axle deflated to the same pressure than to be exactly at the setpoint. Be sure to make every measurement the same way, every time. Consistency and repeatability are greatly improved when the valves on all four tires are from the same manufacturer and lot. This will minimize differences in the rate of flow from tire to tire that cause inconsistent readings.

1. Remove adjustment screw & spring while noting the number of turns the adjustment screw was inserted. Remove ball valve by blowing air into the knurled end of the deflator. Keep one hand over the open end to catch the ball and prevent loss. Make every effort to keep the components of each deflator together for reassembly later.

2. Thoroughly clean inside the deflator’s bore with a Q-tip and rubbing alcohol, then compressed air. Clean all components with rubbing alcohol and compressed air.

3. Apply a fine coating of a high quality, heavy silicone or teflongrease or Vaseline, or a similar lubricant to each ball valve.

4. Insert the stem of the ball valve into one end of the spring and slide this assembly into the deflator, ball end first.

5. Install adjustment screw (the same number of turns before it was disassembled).