Adjustable tire deflator kit from Rugged Ridge
Set includes four brass deflators
Fully inflated tires are great for the road and gas mileage, but they deliver a washboard ride on the trail. Air down your tires for a softer ride and more tread grip.
Your Tire Deator is now set to your preferred deation pressure. Adjustments to you deators can be made at the rate of 3 psi per half turn of the adjusting cap. When the tire pressure and the deator setting is within 8 psi, a manual start may be required by installing the deator then lifting the center pin to start operation. Keep deators clean and dry. Do not interchange components. Remove after deation.
Step 1. Deate a (spare) tire to your preferred deation pressure.
Step 2. With lock ring adjusting cap wound down, screw your tire deator on the valve stem making sure its clean and threads are in good condition.
Step 3. Loosen cap (counterclockwise) until deator pops open, then immediately tighten cap to the position where air stops exhausting.
Step 4. Turn lock ring up to adjust cap and tighten.
Rugged Ridge offers two great kits to fit your lifestyle and budget.
Installation Instruction: 
A Brand Product from Rugged Ridge USA