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Ask Dave: Should I use nitrogen in my tires?

Dear Dave,
We have had our current trailer for 4 years and it came with nitrogen-filled tires. I was told that adding straight air to fill was not an issue. I would really appreciate being educated on the pros and cons of nitro-filled tires. Thank you in advance, Sir. —Joel

Dear Joel,
There has been much discussion over the years on whether nitrogen-filled tires are better or just a lot of hype. I will ask Roger Marble to help address this issue, but I have done quite a bit of research with the RV Safety & Education Foundation as well as The Tire and Rim Association, and here is what I have found.

First, to answer your question, you can add normal air to a tire that has been filled with nitrogen without issue. However, it will eliminate what advocates of nitrogen-filled tires claim as a benefit.

The debate starts with loss of air pressure as the molecules of nitrogen are larger and less likely to pass through the sidewall of the tire vs. normal air-filled tires as the oxygen molecules are smaller. While the molecule size seems to be a fact, there is no documented data showing air loss through the sidewall of tires, as normal air is 78% nitrogen already. Plus, air loss is typically through a valve stem or tire-to-rim seal far more than “seeping” out the sidewall of a tire.

Other stated benefits of nitrogen over oxygen in tires

Other benefits stated are nitrogen-filled tires boost fuel economy, lessen interior tire degradation, and improve safety. Consumer Reports conducted a test of nitrogen-filled tires and normal air-filled tires with the National Highway Traffic Safety Administration (NHTSA) and published a report that can be reviewed here.

NHTSA did confirm that in the year-long test period of more than 30 different models and 16,000 mile tread wear test, nitrogen tires did have a lower pressure loss. However, it was 1.3 psi over the 12-month period. They also found that nitrogen-filled tires had less tire degradation by limiting oxidation caused by normal filled tires. However, it was not substantial enough as normal tire wear would result in replacing the tire way before degradation would take effect.

Their findings: While it is OK to use nitrogen, it has little benefit and normal air is fine and essentially free!

What I personally have found

For the past 10 years I ran a company that manufactured pressure washers and installed them in fast food restaurants all over the country. We had 3 technicians with F-350 trucks and 8K trailers that put on more than 100,000 miles each per year. So we got a lot of “data” over the years regarding tires, axles, bearings and such. Upon purchasing new trailers one year, they came with nitrogen-filled tires complete with the green valve caps!

The first year we had tremendous over-the-road expenses of bearings, axles, and tires. So I had my techs start measuring temperatures every time they stopped for fuel or installation and record the bearing, brake, and tire temperatures so we could determine what was happening before a breakdown.

They would record ambient temperature and then hub, brake, and tire temperature as well as tire pressure. Over the course of 3 years and several hundreds of thousands of miles, we did not notice any significant tire pressure advantage between the two trailers with nitrogen-filled tires and the one with normal air. However, we did notice a slightly lower temperature of the tires that were filled with nitrogen, especially the gooseneck with duals and the inside dual.

I have conducted more than 1000 seminars in the past ten years, including a driving and towing seminar. I recommend owners do this same temp measuring procedure once a day while driving. Owners that come back year after year to attend the seminars have given me feedback that they also have experienced lower temperatures with nitrogen-filled tires in extreme heat conditions.

Nitrogen can be beneficial in extreme conditions

Nitrogen has been beneficial in extreme conditions such as airplane tires that experience drastic temperature changes quickly, as well as racing tires. However, in the normal operation of an RV I do not see the benefit of paying $5 and more for nitrogen.

One last comment. I do put nitrogen in my wife’s and granddaughter’s vehicle tires as they adamantly believe it is beneficial. So if they feel more comfortable with it, I’ll go along with it! However, I warn them both not to get too comfortable and thus not check the air in the tires and perform proper tire maintenance—which I do for them, anyway.

Let’s hear from our readers and Roger Marble on your take of the use of nitrogen.

Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club.

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Roger Marble
7 months ago

RE N2. Many of the claims of benefits are based on the assumption that people do not check their tire pressure as often as RV owners should. Cars have significant excess load capacity while half the RVs on the road are in overload so while a loss of 5% psi will not “kill” a passenger car tire it will, a 5% loss in an RV tire that is already at 0% margin can do damage. RVs should be checking pressure at the start of each travel day and at least once a month when parked. Controlled laboratory tests for normal tire psi loss (permanent gauge on air chamber so even the little loss with each pressure check) show that in general, all tires lose about 1% to 3% per month. Yes, it is mostly O2 that is migrating out due to chemical reactions (yes we do a gas analysis to confirm). When I was racing and had a bottle of N2 I didn’t inflate the truck or trailer tires with N2 as it wasn’t worth the effort and cost. I have 5 posts on my blog that mention Nitrogen. You might review them for more deta

T. Elliott
7 months ago

MUCH more critical to changing tire pressures than N2 or O2 molecules are those H2O molecules. Water and water vapor from a ‘wet’ air can really make a difference. Most nitrogen sources for filling tires is extremely dry. If a gas station tire filling station is spitting droplets of water, you should look elsewhere.

Roger Marble
7 months ago
Reply to  T. Elliott

Yes, moisture is not good. I drain my air tank in my shop but I even made an “air dryer” that fits on the end of my air chuck to get dryer air in my tires.

Lori
7 months ago

Your RV tires are going to need replacing waaaay before ‘oxygen bleed’ is an issue, and you still need to check your tire pressures regularly anyway.
Nitrogen costs waaaay more than air, so who do you think is really benefitting from this trend? (rhetorical question)
Unless you’re consistently stressing your tires in extreme climate temperatures, quite frankly, it’s a bit of a, you-know-what.

Last edited 7 months ago by Lori
cee
7 months ago

Thanks for all that info Dave.

Seann Fox
7 months ago

I buy my tires at Costco and they come with a free nitrogen fill and refills so I’m not going to worry about it at all. I know all aircraft tires are filled with nitrogen and it must be a reason why airlines pay to have them fill that way

Roger Marble
7 months ago
Reply to  Seann Fox

But how often do you take your RV to Costco? Any extra miles to get their N2 does cost you some $ but maybe not much.

Thomas D
7 months ago

Are you having the tires evacuated, meaning draw a vacuum before filling with nitrogen? If not you got (air) in the tires. Why spend the money. Most rv tires will age out before wearing out!

Bob p
7 months ago

As you stated in the article the air we breathe is 78% nitrogen 22%oxygen and 1% inert gases. As Jim b pointed out the oxygen is going to leak out leaving nitrogen and inert gasses. Probably by the time your tires are worn out you’ll be 98% nitrogen. Then you can start all over. Airplanes use nitrogen because they go from 115 degrees to -50 degrees in a matter of minutes and regular air expands and retracts to much to be stable for takeoffs and landings.

Crowman
7 months ago

The biggest benefit is you have to go back to where you bought your tires to have them topped off. Companies make loyal customers this way.

Buckeyebutch
7 months ago

I use it and believe it’s worth using. I was introduced to it back in my racing days and experienced the benefits.

Jim B
7 months ago

Dave, wouldn’t it seem that if the smaller oxygen molicules “weeped” out of the tires that eventually you would end up with nitrogen filled tires anyway?

Dave Solberg
7 months ago
Reply to  Jim B

Good point?! Just keep filling the tire until all the oxygen is gone?

Drew
7 months ago
Reply to  Dave Solberg

🙂

Roger Marble
7 months ago
Reply to  Dave Solberg

Good idea but in testing we found that the % N2 increased less than 2% a year when you add air to make up for the normal loss. Also the loss is not 100% O2 as some N2 will also “leak” out.

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