Friday, December 1, 2023


RV Tire Safety: Is moisture in tires a bad thing? What about in RV tires?

with RV tire expert Roger Marble
The question of nitrogen being used to inflate a tire has been covered in a few of my blog posts and on some other posts on the internet. It is often mentioned that the nitrogen used to inflate tires is “dry” and so that is considered a positive, but I don’t recall anyone getting too specific on why “dry” is better than “wet.”

Before we get into that part of the discussion I want to be sure that everyone understands that any “gas” you buy in a high-pressure tank, aka cylinder, will be “dry,” as the process of separating the gas and compressing it removes the moisture. So if you were to buy a cylinder of CO2 or argon or helium, etc., the gas would be “dry.”

I did a post in May 2012 on How to get dry air for your tires by making your own air “dryer” for less than $20, and for an almost endless supply any time you need it.

There are some companies that sell small cylinders of various gases but you would also need to have a pressure regulator and a source of high pressure (1,000 to 2,000 psi) gas to refill your tank.

But back to the original question of why do we want to keep moisture out of our tires, and why would getting “dry” or at least “drier” air for our RV tires be advisable? By “drier” I am referring to the wet air you can get out of the “free” air at some gas stations where they might not maintain their air compressor or air dryer.

In the past when RV trailers came on bias or tube-type tires we didn’t worry too much about dry air primarily because the tube did a pretty good job of keeping high-pressure moisture out of the tire carcass, plus those bias tires did not have steel belts and were probably just nylon or rayon cord.

The modern radials we use today are almost all “steel belted radials.” So the question is, what happens when you “mix” steel and water? The steel can rust over time. Now in most tires on your car or TV you may drive it almost every day. The driving generates heat and this heat is highest at the belt edge, which would be the most susceptible to moisture. This heat tends to drive the moisture out of the tire rubber.

However, if you let the tire sit for days or weeks, moisture in the air can migrate into the tire structure. Moist inflation air can be driven into the tire structure and over time this moisture can attack the ends of the steel belts and form iron oxide. Rubber doesn’t stick very well to the rusty steel so tears can initiate at the molecular level. Once cracks or tears are initiated in a tire they can only grow and, if allowed to grow long enough or big enough, you can end up with a separation in the tire structure.

Keeping moisture out of the rubber structure is why we also recommend you not park with your tires on wet sand or dirt – the moisture can migrate into the structure if exposed to water for weeks at a time.

Please don’t jump to conclusions and say, “Yeah, but I drive in the rain,” or “Occasionally it rains and my tires get wet.” I am not talking about a few hours of exposure or even a few days. If you drive and heat up the tires it will drive the excess moisture out of the tire. It is weeks or even months of parking in a wet situation that we want to avoid.

Not inflating your tires with wet air (if you get water drops spitting out of the air hose it is way too wet to use except in an emergency) is what we would like to do. If you remove your valve core and what looks like fog or steam or water droplets spits out, you have too much water in your tires. This is under high pressure all of the time so it can affect the life of your tires.

Many after-market tire sealants are water based so using that stuff can hurt your tires.

So that is why inflating your tires with dry or at least drier air is a good practice.


Read more from Roger Marble on his blog at or on



Roger Marble
Roger Marble
Retired Tire Design and Forensic Engineer w/50+ years of experience. Currently has Class-C RV. Previous Truck Camper, Winny Brave, Class-C & 23'TT. Also towed race car w/ 23' open trailer and in 26' Closed trailer. While racing he set lap records at 6 different tracks racing from Lime Rock CT to Riverside CA and Daytona to Mosport Canada. Gives RV and Genealogy Seminars for FMCA across the USA. Taught vehicle handling to local Police Depts



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Tom (@guest_144128)
2 years ago

My vi air compressor creates a lot of heat and moisture. I solved that issue by purchasing a $2.00 paint gun air dryer at harbor freight. Problem solved.

EMORY BRANTLEY (@guest_144091)
2 years ago

I use the on board compressor and air line on my class A coach. I am thinking since the air from the coach has a drier, I am better off than using air from a gas station and such?

volnavy007 (@guest_144090)
2 years ago

In aviation, Nitrogen is used in the tires to avoid starting and/or feeding fires when a tire blows on landing. MAYBE someone in the RV field saw that aviation was using Nitrogen in the tires and thought it would be a good idea for RVs, too?

Impavid (@guest_144122)
2 years ago
Reply to  volnavy007

If a tire blows on landing is all the nitrogen not then gone?

Roger Marble (@guest_144166)
2 years ago
Reply to  Impavid

Impavid, Good observation. While “air” in a tire could theoretically contribute to a fire, I have my doubts. Given that airplanes fly up where any moisture would freeze being sure you have dry air is important. Aircraft tires run very high pressure, some over 200 psi so getting that level from a regular compressor is difficult so using a cylinder with gas compressed to 2,000 psi is the easy way to go.

Lloyd (@guest_75947)
3 years ago

So the tires on my tractor and lawn mower, that are “loaded” with liquid antifreeze, are going to have a short life?

Roger Marble (@guest_76137)
3 years ago
Reply to  Lloyd

Are your Tractor tires Steel belted Radials?. The moisture can attack the steel. But Tractor tires usually do not have the issues of trailer tires as you are on dirt which allows the tire to slip where asphalt results in increased Interply Shear which as I cover in my blog is the force that can end with belt separations. If you keep your lawn mower under 20 mph you should be ok 🙂

Randy Shrimplin (@guest_75836)
3 years ago

Excellent explanation. Living in FL there is no such thing as dry air from a Compressor. I use a Nitrogen tank to top off tires because it’s dry, not because of any possible other benefit (Air is 70% N) but because it’s dry and I can turn the regulator up to 200PSI and get those 120PSI tires inflated quickly.

Roger Marble (@guest_76138)
3 years ago

If you have your own tank of N2 there is no reason to not use it and keeping moisture out of steel belted radials is the goal.

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