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
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.
Read more from Dave here.
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