VIAIR 400P Portable Compressor Kit with Automatic Functionality - 40045

Geoff: Only used for one return to pavement air up.
Will inflate LT275/70R18 - 125/122S (10 ply) ( 33's?) from 19 PSI to 33 PSI in 65 seconds. Did 4 tires, longest time was 72 seconds.

Canada on Jun 15, 2023

Dave Wilenius: Bought in October 2022 but first used this morning (April 2023). Had to top up motorhome tires and as soon as I connected the inflation gun it was leaking enough air out the nozzle, without depressing the grip, enough that I couldn't get it on a valve without disconnecting the hose. Worked fine for the first 5 tires but by the time I got to the 6th the gun was flowing full speed without the grip depressed. Had to pull the hose off and then it was backflowing out the handle. Popping it off the tire was the next step to keep it from bleeding all the air out. Seems like the trigger started bad and then got worse. Will contact Viair and see if I can get a new inflation gun. On the plus side I like the low weight, beefy quick disconnects and the length of the hose was enough to reach all around my RV from the coach batteries which are near the front door.

Canada on Apr 20, 2023

KJ: I purchased this because my son has the 450P RV model. I went with the 400P Auto as I didn’t require the extra hose etc. Excellent product, definitely recommended.

Canada on Apr 20, 2023

Igor: I wish all compressor had auto on/off. To use it, simply turn it on. It will pressurize the hose and will then turn off. Then you can pump the tires. As you pump (press the lever on the air chuck) the compressor detects a pressure drop, and turns on. Very cool. So you just leave it on, and once you are done with all tires you then turn it off.

The hose is nice quality. Light. The connectors on hose are brass.

The air chuck and gauge are heavy duty. You can use a third party one if you like. Standard 1/4 NPT connectors are used throughout.

The unit is very quiet when running, and does not vibrate like crazy. Comes with a nice rubber pad under the metal plate.

Comes with a handy bag.

Overall very happy. Wish it was made elsewhere though, I would be willing to pay extra for that.

Canada on Mar 23, 2022

Pete P: Unpacked the unit, read the paper work and assembled the intake filter and connected hoses. All went together well, but threads on air filter were kinda rough, added a VERY thin coat of light Yamaha lube and it smoothed out and all tightened down nice.

Tested it out on two of my F150 20" tires aired down below 20#, the unit was able to air them up to over 40# both in less than 2.5 minutes. The automatic feature is great as even though the unit is only 33% duty cycle, it shuts down automatically unless its coming up to pressure, or actually pumping air in to a tire. I can't see the duty cycle being an issue with this nice feature and given how I will primarily use it. I should be able to top up all 4 20" tires coming off the beach in about 20 - 25 minutes including setup and pack up and with only about 15 minutes run time on the motor.

Unit is quiet and seem very well built, time will tell how it holds up. The chuck assemble clamp locks down on the valve stem nice and with the handle having an air down / release button its quick to use to air the tires down too.

Unit was only warm to touch after the first 2.5 minutes for the first tire. But even after the cool...

United States on Oct 06, 2018

Joe C.: Perfect for my needs. I previously had an ARB dual compressor which I got included with a used vehicle purchase. Was going to transfer it over to my new Toyota tacoma, but it was just too large to fit anywhere. All the locations that it could be mounted either were planned for a different item. Under the hood where it could mount is the same place my second battery is going. Only other place would've been somewhere under the truck which I am not a fan of, or behind one of the back seats, but by doing so would lose the entire storage behind said seat. Was not prepared to do so, so sold the ARB and bought this.
Sure its not going to fill my tires as fast. The ARB filled my 33" as fast if not faster than this fills my 32" tire on the truck. But its much more compact and its not significantly slower. I have no need to run air tools anymore so this works fine for my needs. Its also much smaller so I can put it behind the seat in the back along with plenty of other gear. At about 1/3 of the price, its more than enough for my needs. Took about 12min to air up from roughly 16PSI back to 30PSI on all 4 tires. My sleeping pad for camping is one of the self inflating as well so no need to...

Canada on Mar 19, 2017

Erin McCann: I love this air compressor.

The product I received is not exactly what was described. I contacted Viair, and found that I had received a newer model than described with the following differences:

1. The air hose is black, and an updated version. Very happy with this.
2. The gun is a 160psi gun, NOT 200psi. This change was made because 200psi is overkill for most people. I prefer the 160psi for my use, the dial is easier to read. I love it.

I have a 2015 Jeep Wrangler Unlimited. This is a perfect compressor for my needs. It is extremely easy to set up and light to carry. The air hose has more than enough length, I can get to my spare without any pulling or stretching.

The compressor is quiet and quick. Using the release valve in the gun, I deflated a tire to 20psi (very quickly, great valve). I then inflated it to 36psi in less than a minute. The compressor worked beautifully. It will automatically shut off if the trigger on the gun is not depressed for a few seconds, and start again when the trigger is depressed.

This compressor comes with the filter assembly ready to attach. It is easy to put on, contains a 2 part filter already, and has two...

United States on Jan 09, 2017

Mr.John: Yes, this thing was made in China but what are we going to do, they all are. I have used this unit several times since I got it and it rides in my SUV everywhere. You can fill up truck tires and smaller items like bicycle tubes just fine. This model has auto shut off so you can use it by only squeezing the triggle, you don't have to keep turning the unit on and off. I like this because I can have the trigger part far away from the pump where the on off swicth is. The unit must be connect to a car battery to work. FYI> I contacted the company here in the USA and they said you "can't" make it run from a transformer if you want to rig it to work from a home recepticle. They also answered a number of other questions, were quick to reply to my email and seemed customer service oriented. I would recommend buying from this manufacturer. The unit seems of very good and solid quality. The hose disconnects from the trigger and from the pump so if you want to change the components out, you could. The triggle with the guage on it is quite nice and heavy and better than I thought it would be. The only complaints I have with it is, I wish I didn't have to have it attached to the car for...

United States on Oct 02, 2010