Viair 300p vs 400p: Which Air Compressor Is Better for Your RV?

An RV tire needs to be filled with air ever so often on a trip, how do you pick between the Viair 300p vs 400p air compressor?

For safe travel and extended tire life, it’s critical that you fill your RV tires to the proper psi, and having a portable air compressor can help you do it. Many RVers compare the Viair 300p vs. 400p to meet their needs. 

Why would you need your own air compressor? It certainly seems easy enough to use a coin-operated air compressor at a gas station. But some RVs require far more air pressure than gas station air compressors can provide. A truck stop might have what you need, but what if you’re low on air and there’s no such facility around? 

That’s why we like having one of Viair’s portable air compressors on hand with enough power to fill our tires and whatever else we need. It’s one of the most popular compressor brands among RVers for good reason. 


But do you need Viair’s 300p or 400p version? Let’s take a look. 

Viair 300p vs 400p: Which Is Better? 

The Viair 300p and 400p are both excellent portable air compressor units. They differ in how much pound-force per square inch (psi) they produce. You’ll choose one over the other depending on your RV weight and tire size. 

As you continue reading, we’ll examine the details of each Viair option to help you decide which is best for you.

A man fills his truck tire with an air compressor - is he using the Viair 300p or 400p compressor?

Benefits of Having an Air Compressor in Your RV

All vehicle tires have a load rating, a letter code indicating how much weight a tire can carry. You can find it on a sticker stating what the tire pressure should be for that tire at that load. It’s essential to pay attention to that sticker.

Tire pressure matters because it influences the shape at which a tire meets the road. 

If there’s too little pressure, the sidewalls flex and can overheat. This is the number-one cause of blow-outs. It also causes uneven wear on the tire.

If there’s too much pressure, there’s less traction, which creates a rough ride and causes uneven wear.

Many RV tires require running 65-80psi or higher for best handling. You might find a gas station with an air compressor that goes up to 80 or 90psi, but there’s often no way of knowing. That alone is a great reason to have an air compressor in your RV!

Besides, you’ll be carrying a lot of weight anytime you’re in your RV. You must check your RV’s tires before you leave and periodically throughout your trip. Having a portable air compressor with you is exceptionally convenient and allows you to top off your tires whenever you want.

Differences Between Viair 300p vs 400p Air Compressors

In choosing between the Viair 300p vs 400p, consider your tires and how they match the differences between the two compressors. Let’s have a look:

Both the 300p and the 400p run to 150psi, and both have a duty cycle of 33%. They each have a thermal overload protector and a hose length of 25 feet to reach all four tires. Both also have an 8-foot power cord, and both use a permanent magnetic motor. 

You can also tuck either one into a nifty, durable storage bag when not in use. That’s a lot of similarities! So what are the differences?

A dirty RV tire is being filled with air - are they using the Viair 300p or 400p air compressor?

Tire Size Inflation

Tire size matters! If you have 33-inch tires, then the 300p may be sufficient for your needs. But if you run 35-inch tires, you’ll need the 400p.

Voltage

The 300p is a 12V unit, but the 400p can run at 12V and 24V. Consider your power supply when determining which will work for you. 

Fill Rate

The 400p will fill your tires faster than the 300p. There’s not much else to say about that! 

Size and Weight

While they’re not dramatically different in size or weight, every bit matters in an RV, so let’s look at the specs of each in this area.  

The 300p weighs 8.60 pounds and has dimensions of 10 x 7.5 x 5 inches. 

The 400p is a little lighter at 8.50 pounds but is larger than the 300p at 13 x 11 x 9.5 inches in size.

RV-Specific

The 400p has a kit made specifically for RVers and will work with the Viair winterization kit (sold separately). The 400p package includes an inflation gun with a 200psi pressure gauge, 30-foot hose, a 30-foot hose extension, sand tray, set of dual heavy-duty battery clamps, 8-foot power cable, inflation tips kit, and fuse holder.

The 300p comes with an open-ended 25-foot tire inflation hose with a 120psi air pressure gauge. Also included are an inline fuse holder, an 8-foot power cable, heavy-duty battery clamps, a three-piece inflation tips kit, an inline fuse holder, a heavy-duty sand tray with vibration isolators, and a deluxe carry bag. 

Specs of the Viair 300p

  • 12 volt
  • Duty cycle max: 33% @ 100 PSI
  • Working pressure max – 150 PSI
  • Amp draw max – 28 Amps
  • Fuse – 40 Amps
  • Inline pressure gauge – 100 PSI
  • Dimensions – 9.80″L x 4.90″W x 7.50″H
  • Net weight – 8.60 lbs

Specs of the Viair 400p

VIAIR 400P Portable Compressor
  • 12 VOLT Operated - 150PSI Max Working Pressure, engine must be running during use.
  • 2.3CFM Free Flow @ 0 PSI. The air hose length is 25 feet
  • 12 volt and 24 volt
  • Duty cycle max: 33% @ 100 PSI
  • Working pressure max – 150 PSI
  • Amp draw max – 30 Amps
  • Built-in pressure switch – 120 PSI on, 145 PSI off
  • Fuse – 40 Amps
  • Dimensions – 11.25″L x 4.00″W x 7.00″H
  • Net weight – 8.50 lbs

Viair 300p vs 400p: Which Is Better for You? 

While the Viair 400p is the best all-around deal, your choice really depends on the size of the tires you’ll be filling. If you’re filling 35-inch tires, you’ll need the 400p. If you never fill tires larger than 33 inches, you can choose between the 300p and the 400p. 

Bear in mind that the 400p will fill your tires slightly faster, offer you a longer hose, and only with the 400p can you use the optional RV winterization kit.

Either way, a portable air compressor is a great tool to have on hand, and Viair is an exceptional brand. But given a choice between the 300p vs 400p, the Viair 400p comes out ahead for only $50 more.

Last update on 2021-09-20 / Affiliate links / Images from Amazon Product Advertising API

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