DIY 4 Tire Inflation & Deflation System – Build Guide

When hitting the trails, you want lower tire pressure in order to maximize traction and help smooth out some of the rougher patches.

When your tires are at full PSI, you will have a rough ride and less traction off-road. How low you go depends on your particular tires, wheels, and suspension set-up. I have a 2015 Toyota 4Runner Trail edition with KO2s and keep them at 40 PSI for everyday driving.

Airing Down for Off-Road

When off-road, I typically go down to 20 PSI, but I have gone as low as 15 PSI. I have seen articles that suggest going down a little further (10-12 PSI) is acceptable, but I have not gone below 15 PSI.

Going too low carries a risk because most wheels do not have a bead lock. Going too low can break a tire’s bead lock, damage the tire, or damage the wheel itself. Short story: Don’t go down too low.

Airing up for On-Road

Once you’re off the trail and back on pavement, it’s critical to get back up to standard tire pressure as soon as possible. Running underinflated on the pavement can cause excessive wear, poor handling, and damage several parts of your truck, including the tires.

That means you either have an onboard air compressor or know where the nearest gas station is located, and hope it has air available.

Onboard air compressor

I have mounted a Viair 450 p (model number 45043) that is rated for continuous service but with a low cubic feet per minute rating for air flow: 1.8 CMF. Compare that to the 6.16 you will see with the dual ARB compressor.

The unit is portable, and I used a set of wing nuts to keep it in place behind my seats and in front of my drawers. I have it connected to my house battery with a 30-amp fuse. I can easily take it out to use in another car or reduce weight when I don’t need it.

The compressor is in such a convenient spot and easily accessible that I have kept it in the 4Runner from the start. It comes with an air chuck, gauge, and an air hose that extends around the 4Runner. I’ve had no issues with it, but there are several great compressors out there that offer continuous service.

I mentioned earlier that this particular unit has a low CFM (Cubic Feet Per Minute), which, according to VIAIR, is the trade-off for continuous service. I have not seen any major issue with the low CFM, but it certainly does take time to inflate all four tires. Most of the time is spent connecting and disconnecting the four individual tires.

DIY 4-Way Hose System

That’s where a 4-way inflator/deflator can help.

There are a few products out there that can inflate and deflate all four of your tires simultaneously.

I’ve seen products on Amazon, Harbor Freight, and other plug-n-play inflation/deflation kits, but while working on another air compressor project, I had leftover spare parts and wanted to build it myself.

I don’t think I saved a lot of money doing this myself since you can find a product for less than $100, but I’ve added a few features that make my version a little more productive.

Parts list:

• 2x 25 foot ¼ inch air hose (Husky Polyurethane air hose)
• 4x Standard Bore Lock-On Air Chuck – Check Price
• 2x ¼ inch Brass hose Barb Y Manifold Fitting – Check Price
• 1x ¼ inch NPT Female/FPT x 4 Way Cross Intersection Brass Fitting – Check Price
• 1x (0-60 PSI) Tire Pressure Gauge – Check Price
• 1x ¼ inch MNPT Male Tank Valve (Schrader Valve) – Check Price
• 1x Husky T Connector
• 1x Husky shut-off valve
• 1x ¼ inch quick connect coupler Male
• 1x Viair 450p air compressor – Check Price
• Several single-ear hose clamps for each barb connection
• Plumbers’ tape to seal threaded connections

The kit uses 2 x 25-foot long ¼ inch Husky Air hoses. For the 4Runner, you will have a little leftover hose, but not much. I used 2 x 25-foot sections instead of one 50-foot section to utilize the four pre-crimped ends with hard rubber end protectors.

I decided to use 1/4″ hose and 1/4″ connectors all around—mostly because I had a lot of 1/4″ leftover supplies. I’ve seen articles that talk about using 3/8 “hose to improve CFM, but that would mean I would need to use 3/8 “connectors all around to see that benefit.

All the hardware connects with 1/4″ inch hose barbs or standard 1/4” NPT (National Pipe Thread) threaded connectors. I connected the barb connectors using single-ear hose clamps.

4-way brass fitting with air gauge

The heart of the system centers on a basic 4-way brass fitting with an air gauge going up to 60 psi on top. The two main sections of the air hoses are connected with a brass T compressed air fitting from Husky. On one side, I’ve installed a standard Schrader valve, and on the other, a 1/4″ quick-connect coupler with an in-line shut-off valve.

To deflate all four tires at the same time, I open the valve while keeping an eye on the pressure gauge. All four tires will deflate quickly and wind up at the same psi, eliminating the need for a quick deflator that removes the Schrader valve stem.

Note: You should close the shut-off valve to stop the air flow to check for accurate pressure.

To inflate all four tires, I have a choice between the Schrader valve, which allows me to use any standard tire air inflator, and a 1/4″ quick-connect air hose coupler, which allows me to connect directly to my compressor.

I have not seen this on other kits, but I find the option very useful. It’s the main reason I opted to build the kit myself. I tried to use a couple of different automatic pressure regulators but found them either too hard to adjust or never as accurate as I would have liked.

Given that and the added cost of a regulator, I decided against using one. I find it’s easy enough to keep an eye on the pressure gauge while inflating. I can quickly close the shut-off valve using the coupler or stop the airflow using a standard air chuck. All four tires will have the same PSI. The complete system rolls up into a compact package for easy storage.

Barb Connectors

Standard bore lock-on air chucks

At the end of each section, standard bore lock-on air chucks are threaded on that fit a standard Schrader valve found on most tires. I found these chucks on Amazon and liked their features—they are easy to lock by pushing the collar on the valve and easy to remove by pulling on the collar.

Once locked, these chucks have 3 points to grab onto the valve, making for a secure connection. They are a little pricey, but they are a great product. There are plenty of effective alternatives to help with costs.

Brass T compressed air fitting

Milton Male Tank Valve (Schrader Valve)

Quick connect coupler

Final Thoughts

With the shut-off valve in the closed position, the kit is airtight. I can attach and detach one tire at a time without affecting the remaining connected tires. Deflating all four tires at the same time is very fast.

Tire inflation will also take less time since you don’t have to connect and disconnect the air chuck to move it from one tire to the other. However, the compressor’s CFM capacity will ultimately determine how long it will take to inflate all four tires.

I find the 4-way tire inflator/deflator kit very easy to use and set up. Putting it away requires a little effort but all worth it to save some time. The kit requires very little maintenance – just keep the chucks clean and free of any obstructions. Try not to kink those and keep it away from a heat source like an exhaust pipe.