Do You Need One? Which One is Right for You?
Class B Travel Trailer Class C Class A
And Passenger And Or Larger Class C
Vehicles 5th Wheel 5th Wheel Large 5th Wheel
All tires fluctuate in air pressure even when they're parked, and RV tires are no different in this regard. Regular checking and adjusting of tire pressure is something every RVer should do for their own safety and that of others, as well as to protect their home on wheels, so the VIAIR 450P-RV Portable Air Compressor is our #3 Top Pick!
We had a hard time deciding between the TireMinder A1A TPMS and the VIAIR 450P-RV for Top Pick #2 and #3, respectively. For us, the two are both critical components and equally important to have aboard our motorhome. Our safety and those around us on the road are paramount.
As an avid motorcyclist with a few hundred thousand miles under my belt, many of which were on tracks in excess of 100mph, I may have a more unique appreciation for the importance of properly inflated and maintained tires than that of someone who has only driven a passenger vehicle at normal speeds. An under-inflated tire or a blowout on a motorcycle can be fatal...period, end of story. Seldom is slowly pulling over to the shoulder of the road an option when you're on two wheels and such an event occurs. Often the first warning of an under-inflated tire is when you lean into a corner and the front or rear of the motorcycle "washes out" and slaps you on the pavement with no chance of recovery.
But enough about motorcycle tires, we're here to talk about RV tires and tire pressure!
So why do we have both a TPMS and a portable RV air compressor?
Why not just check your tire pressures on the TPMS and, if any are low, pull into a gas station and add air?
You will likely turn off your TPMS monitor while parked at a campground or a boondocking location. When you turn it back on to head out, most take a couple of minutes to re-read all of the sensors, but will show the last read pressure from when you parked. So while you may think everything's good to go, one or more tires could be low on pressure without you realizing it before you head down the road.
Not all gas stations have air pumps available, so you have to find one that does (and I don't think "there's an app for that!" At least I haven't seen one or heard of one.
If you are lucky enough to find a gas station nearby with an air pump, it may not be accessible with a large RV and/or may not have a long enough hose to reach all of the necessary tires without a lot of moving and turning around which would be a major hassle, especially in some of the smaller stations' parking lots.
Even if you find a station close by that 1) has an air pump, and 2) is accessible with your RV, many of the current coin operated (or free) electric air pumps at these stations are limited to 55psi, far from the required pressure of almost all RV tires and not even sufficient for many truck tires.
If you get lucky and all of the stars and moon align to find the perfect gas station with an air compressor you can get to and it is capable of the PSI you need for your RV tires, DO NOT use or rely on the air pump's gauge! According to NHTSA, the National Highway Traffic Safety Administration:
* 34% of the gauges at lower traffic air pumps over-report by more than 4psi @ 35psi
* Gauges at medium-high traffic stations that charge a fee are 4.4x more likely to over-report by more than 4psi @ 35psi
a. 75% of those pumps over-report by more than 6psi @ 55psi
b. 25% of them over-report by more than 8psi @55psi
For simple, rough math as it pertains to an RV, extrapolating the variance above for 25% over-reporting by 8psi @ 55psi, assuming the variance is linear as the psi increases (which the NHTSA report suggests), a 5th wheel tire that requires 85psi would be off by 12psi, which is 14%! Think about that for a second! You think you're rolling down the road with 85psi in all of your tires, but in reality they are all severely under-inflated at 73psi!! The acceptable deviation from the recommended tire pressure is only +/-3%, so in the example above 82psi would be the minimal acceptable tire pressure, not the 73psi as a result of using a gas station air pump gauge.
Under-inflated tires don't only create a dangerous situation and increase the risk of blowouts, especially in hotter ambient temperatures, but also have a direct impact on your fuel economy. And this holds true for vehicles being towed as well!
* For every pound of air below your tires recommended psi you reduce your fuel efficiency by .2%, so if your tires are 10 pounds low your losing 2% fuel efficiency.
So why not just over-inflate so you don't have to worry about it? Well, over-inflation is bad as well. While it may help you with fuel economy it can cause crowning where the center of the tire wears out unevenly from the rest of the tire. Also, over-inflation can cause poor handling, diminish traction under braking, and provide a much harsher ride. Again, the wear issue holds true even if the vehicle is being towed.
For all the reasons listed above, the best course of action is to carry a portable RV air compressor with you. We use ours EVERY time to check all of our tires before we leave a campground. I used to check the tires with a separate pressure gauge and then get the VIAIR 450P-RV Air Compressor out if any needed air. After a couple months doing that I now just get the air compressor out and check all the tires with it. Do you know why? Because there is ALWAYS at least one tire that 3-4psi low, sometimes even more depending on temperature changes. That doesn't mean the tire has a leak or is damaged in any way. Air contracts and expands with temperature, it's that simple. And when you drive down the road temperature increases, you park and it decreases, but now always to exact proportions resulting in the small psi variances over a week or two.
There are different versions of the VIAIR RV air compressors, each rated for specific classes of RV's. Here is the breakdown of each to help you determine which one is right for you.
This air compressor is ideal for passenger vehicles including vans, SUV's and small trucks, as well as Class B RV's. While called a standard duty cycle, this is really a light duty cycle when put in context of RV tires, even the larger Class B tires. It will suffice and allow you to get your tires to the required pressure, but the duty cycle this compressor is rated for may require a cool-down period during inflation if you are adding significant amounts of air to all 4 tires. For anyone traveling often in a Class B, I would recommend stepping up to the 300P-RV simply for the heavy duty cycle to not have to worry about the compressor cutting off for cool-down in the middle of checking and inflating the tires.
Standard Duty Cycle: 25 min @ 30 PSI
120 PSI Max
Inflates 255/70/19.5 tires from 80 to 90 PSI in less than 2 minutes
The 300P-RV comes with a heavier duty cycle that is more suitable for Travel Trailer and 5th Wheel tires that not only require higher PSI inflation, but also hold more volume than typical Class B's due to the tire size. That said, this is also great option for Class B RV's for faster inflation without any worry over overheating the VIAIR 88P by extending past its duty cycle and then having to wait for it to cool down. Also, there are some 4WD versions of Class B's now on the market that are running much larger tires requiring higher PSI and holding far more volume that standard passenger vehicle tires. The 300P-RV, or even the 400P-RV are great solutions for vehicles like those.
Heavy Duty Cycle: 33% @ 100 PSI
150 PSI Max
Inflates 255/70/19.5 tires from 80 to 90 PSI in just 44 seconds
Stepping up to the VIAIR 400P-RV Portable RV Air Compressor is where things start to get serious. The 400P-RV has a heavy duty "fast fill" cycle, flowing more air volume at higher PSI that the previously mentioned models. As well, the 400P-RV has an automatic start/stop which keeps the compressor from running continuously while you move from tire to tire, check pressure, remove valve stem caps (or hopefully TPMS sensors instead!), etc. In our opinion, this is the ideal air compressor for all RVs up to, but not including, Class A and Super C motorhomes.
Fast Fill Duty Cycle: 33% @ 100 PSI
“Stop/Start” Automatic Shut-off Function
160 PSI Max
Inflates Most Class C tires from 80 to 90 PSI in just 46 seconds
Last on the list is the VIAIR 450P-RV, the most powerful air compressor of the group. This compressor has a continuous duty cycle, meaning it can run continuously as long as necessary (up to 40 minutes at 100%) to get the job done! This makes it the ideal solution for all high pressure, large volume RV tires as seen on most Class A's, Super C's, some triple-axle 5th wheels, and even larger Class C's. Like the 400P-RV, it comes with an automatic start/stop to keep it from constantly running when there is no demand for air on the compressor. As well, both the 400P-RV and 450P-RV come with all of the necessary accessories for a big rig air compressor including a 30' hose and a 30' extension hose for a total reach of 60' making it easy to reach all tires without having to move or reposition the air compressor, a 45 degree extended-reach chuck for dual rear tires, and 90 degree chuck for easier tire inflation while standing.
Continuous Duty Cycle: 100% @ 100 PSI
“Stop/Start” Automatic Shut-off Function
160 PSI Max
Most Class A tires from 80 to 90 PSI in just 50 seconds
Can be operated continuously for up to 40 minutes at a time before needing to restIncludes Primary & Extension Air Hoses
Stay safe out there and check your tire pressures before every move. It only takes minutes and can be the difference between a great travel day and a very bad one. Remember, your tires are the only thing between you and the road!
Class B Travel Trailer Class C Class A
And Passenger And Or Larger Class C
Vehicles 5th Wheel 5th Wheel Large 5th Wheel
Check out other RV Portable Air Compressor options here: https://amzn.to/2v9IBhV
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