Portable Air Compressor for Truck and RV tires

The Viair that I have pumps to at least 200 lbs because the value set on my air tank for my air horns. The tank has a chuck for an air hose

A while back I did a real world comparison of the Viar 400P RV and the Viar 450P. One interesting note is that with compressors the lower the amp draw rating the more powerful the compressor is. For most other appliances the opposite is true.

You can read it here:
http://www.irv2.com/forums/f52/viair-400p-rv-and-450p-comparison-234981.html

I am copying my post here:

Hello everyone,

I finally gave in to find an easy solution to topping off my tires without turning on the engine. I have been reading good reviews about the viair 12 volt portable compressors and wanted to give them a try. The one problem was, I could not decide which of these two models would work best so I purchased both to test and would return the one that does not perform best.

Here are the specs for the two models:

Model 400 P-RV Automatic-
Duty cylce = 33% (can run for 10 minutes then must rest for 30 minutes)
CFM = 2.54 CFM
Advantage = greater CFM
Disadvantage = shorter duty cylce
Max amp draw = 30 amps

Model 450 P Automatic-
Duty cycle = 100% (can run continuously without stopping)
CFM = 1.66 CFM
Advantage = 100% duty cyle
Disadvantage = Lower CFM
Max Amp draw = 20 amps

(note on amp draw and compressors: the more efficient the compressor is the lower the amp draw is, so the lower number here is better than a higher number)

To be clear, I will never use this compressor to fill a flat RV tire, only to top them off with 5 to 10 psi. I needed something to reach 120 psi without struggling. My main concern and question with the 450P was would it take a ridiculous time period to top off a tire compared to the 400P RV.

Method:

I purged one tire to 117 psi and clocked the time to fill this tire to 122 psi. The ambient temperature was 75 degrees Fahrenheit

The 400 P-RV took 1 minute, 35 seconds.
The 450P took 1 minute, 55 seconds.

As it turned out the difference in time was not too significant. My choice was to keep the 450P in order to have the 100% duty cycle and will be sending back the 400P-RV.

I was particularly curious about the performance of these two models when I first watched a video recommending the 400P-RV from the RV GEEKS. I wonder if they ever tested the 450P model.

I hope this information is helpful to some and look forward to hearing your input and opinions on this subject.

Hi S n L,

Great report! ty.

S-n-L wrote:



To be clear, I will never use this compressor to fill a flat RV tire, only to top them off with 5 to 10 psi.

Method:

I purged one tire to 117 psi and clocked the time to fill this tire to 122 psi.

I hope this information is helpful to some and look forward to hearing your input and opinions on this subject.

Extensive tests!..:C

However, since you were into testing - *why not* deflate your spare (or other tire), as if you had a flat, and see what kind of results you can achieve? - (Never say "never" - as you stated).

Also - for folks with MHs (with an on-board gen) - how about the
above tests (time) with a 110V compressor? ("purged" & flat)..:@

Lots of options for capable 110V compressors from various sources - including Harbor Freight.
Besides the "on-the-road" uses, very handy at home...;)

BTW - before I discovered the benefits of a C02 system - for topping-off or full flats, I have (in the past) carried a 110V pancake style compressor/s (135-150psi capable) - which (IMO) were far superior to the 12V variety.

~

Why would you refill and use a tire that had gone completely flat without getting it checked out?

Guess it depends what you want the compressor for. Personally, I find the Viair about perfect for on the road use. It takes up very little room and when I am staying somewhere for an extended time, I can drop the rear tires on my truck down to 50 psi because I know this little compressor will get them back up to 80 in short order.

Downsides, You can't set the output pressure so I wouldn't use it to blow out water lines and with no tank, it can't be used for air tools.

TakingThe5th wrote:
VIAIR 400P-RV Automatic Portable Compressor. Works on 12 volts. Expensive but works well. Does not plug into cigarette lighter, you need to clamp directly to battery. Comes with plenty of hose.

Can you clamp it to the deep cycle battery on the front of a travel trailer or does it have to be clamped to the truck battery?

texasAUtiger wrote:

Can you clamp it to the deep cycle battery on the front of a travel trailer or does it have to be clamped to the truck battery?

States "engine must be running during use".

As far as connecting it to the deep cycle battery, the RV should be plugged into shore power if connecting to the RV battery. If this is not possible than I would connect to your truck with the truck running.

I am mostly plugged into shore power so run it off my coach batteries.

S-n-L wrote:
If you are thinking about a Viar Compressor there are two models to consider, the 400 and the 450. Before my purchase I called the tech support at Viar and told them I had 22 inch tires and they strongly recommend the 450 due to the 100 % duty cycle. The 400 has a 30% duty cycle. I purchased the 450P model based on the tech's advice.

Just something to think about.

If anyone is phone-call-adverse (cough, me, cough)- their website has an online chat and you get the same very helpful responses there. I have nothing but high praise to say about those folks.