Viair 300p vs 400p (1500) Guide

What Is A Viair Compressor?

Viair is the leading manufacturer and distributor of high performance DC air compressors for all mobile pneumatic applications. The company has been in business since 1998 and seeks to be the industry standard in the automotive market with regard to compressors.

Viair 300p vs 400p (1500)

According to their Website, this is the company’s identity and mission:

“VIAIR Corporation offers the most comprehensive line of D.C., fractional horsepower, oil-less air compressors & air accessories for both on-road and off-road automotive enthusiasts. Our quality-engineered compressors and components have become the industry standard for both 12-Volt and 24-Volt automotive aftermarket applications worldwide.

VIAIR compressors are currently deployed at every corner of the globe, in the world’s harshest environments – from arctic climates to the world’s most unforgiving deserts. Offering the most depth and breadth for mobile air source needs in our category. For over 25 years, VIAIR has become the most trusted and recognized brand by consumers worldwide.

In addition to servicing all Automotive Aftermarket segments, VIAIR is also active in many other end markets, ranging from Industrial, Mining, Energy, Agriculture, Construction, First Responder, Education, to Healthcare.

Our promise is to consistently deliver performance, reliability and value to our customers. Our goal is to provide the ultimate Vital Air Source – the heart of any mobile pneumatic system.”


How Does An Air Compressor Work?

Mark from RVing Today TV reviews the Viair compressor and shows us the benefits and use of having one. Since Mark has a Class A, he demonstrates the use of the Viair 450P, which is exclusively for Class A motorhomes:

The Viair RV compressors are designed to have the capacity to inflate RV tires to the proper pressure (when taken out of storage, before a trip, when the TPMS indicator goes off or during drastic elevation or temperature changes). These compressors are also compact enough to take along in an RV, because, let’s face it, space is a precious commodity for RVers.

Improper tire pressure can cause blowouts and serious damage to the RV, as well as derailing your travel plans for days, or even weeks (if serious damage is done to the RV body due to the tire blowout).

Mark recommends against using air refill stations at gas stations due to inaccuracies, as well as the fact that one should measure and refill the air on “cold” tires (not after driving for hours).

The Viair unit is small, manageable and lightweight, comes in a storage bag and with a long hose that can reach all tires (this is a huge benefit), as well as a 90-degree extended adapter that makes it possible to inflate your tires while standing up. This is so nice, no more sore back from bending down for what seems like hours!

No worry, though, because the Viair 450P can fill up a tire from 80 to 90 PSI in under one minute! That’s a huge difference compared to having to fill up at a gas station for 5-10 minutes per tire. Viair is also the only brand on the market that can reach pressures up to 150 psi. The compressor has a 40-minute recharge time.

How to use the compressor:

  1. Attach the heavy-duty clamps to the RV battery
  2. Start the engine
  3. Connect the tire chuck to the valve stem and turn the unit on
  4. The handle has a gauge on it to see what the current pressure is and you can observe the pressure increase to keep an eye on your goal pressure
  5. Once you are at your goal psi, turn off the compressor and move on to the next tire (if applicable).


When mounting your compressor in your RV for more permanent storage and prevention of potential theft, some people claim that you could mount the compressor in any direction, because it does not require any oil. However, even with an oil-free compressor, mounting should always be the right way up. This is for a number of reasons. An upside down compressor can place unexpected stress forces on parts of the machine and cause additional wear. An upside down motor can cause heat dissipation issues, and risk overheating.

Therefore, one should consider twice whether they want to use the unit in a way that will severely shorten its lifespan.

Since the Viair RV compressors are so small and light-weight, one can easily keep them in their storage bag and place them anywhere in the storage bay for easy access.

Benefits Of Having An Air Compressor

One can use an air compressor for several applications:

The most obvious one is to refill tires to the appropriate tire pressure without having to find a gas station that 1. has a tire air station and 2. allows a large RV to pass through safely and easily. In addition, you don’t want to check and inflate “hot” tires anyway, so having a compressor kit ready before you begin your trip makes most sense.

Furthermore, the gas station air compressors are often inaccurate or not functioning due to overuse and abuse of others.

You can slow connect to 12V or 24V and have the accessibility convenience. An air compressor is also handy for select tool applications, as well as for airing up kids’ toys (balls, bikes inflatables), golf carts, ATVs, or even air mattress for extra guests.

Added benefits of an air compressor are that you can use it to check for freshwater plumbing leaks (using blowout plug), and you can winterize your RV tires (when the pressure drops during temperature drop).

Overall, Viair is the market leader on lightweight yet powerful RV compressor units. Many RV owners switch to this brand after they see the benefits and unparalleled performance (compared to other, slower and bulkier units).

Viair Air Compressor Specifications

There are many different Viair air compressors one can choose from:

  • Adventure Series Overlander OBA System
  • Toy Hauler Portable Tire Inflator or OBA System
  • Portable Tire Inflator
  • Right Onboard Air System
  • RV Tire Inflator
  • “C” Compressors

The RVs Portables are designed specifically for the RV market and have been tested for safety on RV tires. With regard to the RVs Portables, there are four different models to choose from:

  • 89-P RVS Portable Tire Inflator for Class B RVs
  • 300P-RVS Portable Tire Inflator for Towables
  • 400P-RVS Automatic Tire Inflator for Class C RVs
  • 450P-RVS Automatic Tire Inflator for Class A RVs.

The company also offers an RV Winterization Kit.

Let’s look at the details of each of the RV Portables:

  • 89-P RVS Portable Tire Inflator for Class B RVs
    • From 80 PSI to 90 PSI in under 2 min
    • 12V
    • Air Hose with 120 PSI Pressure Gauge
    • LED Work Light/Power Indicator
    • Dual Battery Camps
    • Solid Brass Twist-On Tire Chuck
    • 3pc Tire Inflation Tips Kit

  • 300P-RVS Portable Tire Inflator for Towables
    • From 80 PSI to 90 PSI in 44 sec
    • Thermal Overload Protector
    • 5-in-1 Inflator/Deflator Air Hose with Inline 150 PSI Gauge
    • Aluminum Sand Tray with Vibration Isolators
    • 40-Amp Inline Fuse Holder
    • Dual Battery Clamps
    • 3pc Inflation Tips Kit

  • 400P-RVS Automatic Tire Inflator for Class C RVs
    • From 80 PSI to 90 PSI in 46 sec
    • Thermal Overload Protector
    • Automatic Shut-Off Function
    • Primary and Extension Air Hoses
    • Vibration-Resistant Diamond Plate Sand Tray
    • Heat Shielded Quick Connect Coupling
    • Gas Station-Style Tire Inflation Gun with 160 PSI Gauge
    • Heavy Duty Dual Battery Clamps with Inline Fuse
    • 45-Degree Extended Reach Chuck (for Dual Rear Wheels)
    • 90-Degree Twist-On Chuck

  • 450P-RVS Automatic Tire Inflator for Class A RVs
    • From 80 PSI to 90 PSI in 50 sec
    • Thermal Overload Protector
    • Automatic Shut-Off Function
    • Primary & Extension Air Hoses
    • Vibration-Resistant Diamond-Plate Sand Tray
    • Heat Shielded Quick Connect Coupling
    • Gas Station-Style Tire Inflation Gun with 160 PSI Inline Gauge
    • Heavy Duty Dual Battery Clamps with Inline Fuse
    • 45-Degree Extended Reach Chuck (for Dual Rear Wheels)
    • 90-Degree Twist-On Chuck

Comparison Of Viair 300p Vs 400p 


  Viair 300P Viair 400P
Cost From $189 (Amazon) From $239 (Blackhawk Motorsports)
Tire Size Inflation Up to 33-inch tires Up to 35-inch tires
Voltage 12V 12V
Fill Rate (from 80-90 PSI) 44 sec 46 sec
Size and Weight Dimensions: 9″L x 4.9″W x 7.5″H

Weight: 8.7 lbs

Dimensions: 10.87″L x 5.83″W x 7.48″H

Weight: 10.75 lbs


Viair 300P is designed for towable RVs, such as trailers, fifth wheels and toy haulers whereas the 400P is designed for Class C RVs.

Which Is The Better Viair Compressor?

As mentioned above, each compressor is designed for a different application and tire load. Viair 300P is designed for towable RVs, such as trailers, fifth wheels and toy haulers whereas the 400P is designed for Class C RVs.

To compare the two does not make much sense, because each one is designed for a different application; a fifth-wheel owner will need the 300P while a Class C RV owner would purchase a 400P. Both units can also help with additional applications, such as airing up inflatables, ATV or golf cart tires.


How long does a Viair compressor last?

When referring to lifespan, it depends on how well one takes care of the unit. A compressor can last anywhere from 5-15 years, depending on maintenance and usage.

When referred to the unit’s duty cycle, it means how long one can run the unit in a full cycle and that amount is about one hour.

Where are Viair compressors made?

They are made in China.

Do Viair compressors need oil?

No, they are oil-less and thus, can be mounted in any position.

Are Viair compressors waterproof?

These compressors are splash- and moisture-resistant, but not waterproof.

I removed the headers and placed them into an easy overview table instead for better comparison. I hope that’s ok.

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