How Water Harms Your Tires

On November 29, 2012, in Nitrogen Tire Inflation, Tire Care, by allisonmreilly

water in your tiresMany of those who are against nitrogen tire inflation will tell you that keeping an eye on your tire pressure and even using an air compressor at home to do it yourself will achieve the same results of nitrogen, but at a fraction of the cost. Although nitrogen tire inflation isn’t a replacement for checking your tire pressure regularly, many DIY options aren’t the best because they give you air that still has moisture in it. Here’s why that moisture is so bad, and why most air compressors and other tire-filling tools don’t do a good job of getting rid of all that air.

There is Never Zero Humidity in the Air

Even if you live in a particularly dry or cold climate, there is still some level of moisture in the air. There’s always water in the environment, and as long as there is water in the environment, there is always some level of moisture in the air. Using an air compressor to fill your tires on a dry day or a really cold one may help to an extent, but it doesn’t mean that the air you’re putting in your tires is dry.

Most Air Compressors Don’t Have an Air Dryer

Many of them come with an air filter, which does help in getting rid of moisture as well as dirt and grime, but it’s not the same as an air dryer. Air dryers are not only sold separately, but most of them are industrial-sized and several thousand dollars, something that the typical driver can’t afford and that most gas stations and auto shops don’t have. An efficient air dryer can get rid of the moisture so that you fill your tires with dry air, but this simply isn’t the case most of the time. The best someone can do with air compressors is to drain water from the air lines, but all that indicates is that the air you are putting into your tires has moisture in it.

Air Compressors Don’t Eliminate Water from the Air

Air compressors actually concentrate the water that’s in the air instead of removing it. This means that air compressors at the gas station also contain water and aren’t a better solution than using your own compressor in the garage. In fact, the air compressors at the gas station are probably worse if the gas station or the auto shop doesn’t do anything about the moisture problems, like drain water from the lines. The water vapor from air compressors accelerates rust and corrosion inside your tire and on the axle.

Umm… There’s Water in Your Tire

That moisture can accumulate over time, and then you’re driving with water in your tire. Not just water vapor, since when your tires cool the vapor turns back into the liquid. A variety of things can happen here. If it’s cold enough overnight, that water is freezing in your tire. In the first few minutes of the drive, that water is sloshing around, which can’t be good for handling or tread wear. Granted, liquid water in your tires doesn’t stay that way for long, but that doesn’t mean the harm goes away.

Water vapor also absorbs and holds heat, which only increases as you drive and as temperatures heat up outside. Tires inflated with air tend to run hotter and to fluctuate in pressure more, increasing the chances of a blowout and the chances of an inaccurate reading when checking tire pressure. Also, when it changes from liquid to vapor, water expands tremendously in volume, decreasing its handling, tire life, and fuel efficiency.

Overall, this argument that you can fill your tires at home with an air compressor and achieve the same result as nitrogen tire inflation is just nonsense. The technology that exists for air doesn’t provide dry air, while a nitrogen tire inflation machine does provide dry, inert nitrogen. Please still check your tire pressure regularly, but filling you tires on your own doesn’t compare to nitrogen tire inflation.

nitrogen tire inflation myths paper

nitrogen in tiresWhat’s Wrong with Their Study?

Consumer Reports is a highly respected magazine that publishes reviews and comparisons of consumer products and services based on reporting and results from its in-house testing laboratory and survey research center. Most of the time, Consumer Reports has great content and does a good job in their testing and research processes. However, the magazine conducted a nitrogen air loss study between 2006-2007 (it was a year-long study), and we think that this study isn’t a true representation of the benefits of nitrogen tire inflation.

Consumer Reports tested nitrogen air loss by evaluating pairs of 31 tire models of H- and V-speed rated, all-season tires, filling one with 95% nitrogen and the other with regular air. Their use of a variety of tire models is good, but that’s not the problem. The problem is in how this study was conducted. Consumer Reports filled and set the inflation pressure at room temperature to 30 psi (pounds per square inch); set the tire outdoors for one year; and then rechecked the inflation pressure at room temperature after a one year period.

Why the Nitrogen Tire Inflation Results are Skewed

The Consumer Reports study found that nitrogen does reduce pressure loss over time, but the reduction is only a 1.3 psi difference from air-filled tires, which was considered minimal. However, since these tires weren’t tested under normal operating conditions, which not only affect tire pressure retention (which is what the test was meant to study) as well as what that tire pressure retention can mean under normal operating conditions (such as a smoother, safer ride, or a lower likelihood for a blowout, or improved fuel economy), this 2006-2007 study only tells half the story. Although it found that the tires filled with nitrogen better retained their proper tire pressure than the air-filled ones, the test and its results don’t do a good job of what this means, making it too easy to argue that it doesn’t mean anything at all.

There are Holes in the Q&A Too

As a follow-up to the tons of comments the article received (most recent comment from April 2012) a Q&A was published just a week after the original article to respond to all the comments and to address some of the issues that were brought up. We found a few holes in that article as well. Here’s one example:

Q: I just thought I’d remind everyone that nitrogen makes up like 75-78% of ambient air, so air verse nitrogen should make little or no difference.
Yes, nitrogen makes up most of the air — about 78% as you point out. Think about this, though: if you fill your tires with air, the oxygen is more likely to permeate out of the tires before the nitrogen and over time you end up with a higher concentration of nitrogen. I have not checked this but it seems possible.

Sure, it’s possible, but you still end up with an underinflated tire. A tire of pure nitrogen, but not at proper tire pressure is just as bad as   an underinflated tire that has regular air in it. Choosing this method to get your “nitrogen tire” simply because it’s cheaper doesn’t mean that it’s better for you or your tires.

There’s Nothing Wrong with Nitrogen Tire Inflation

This study from Consumer Reports is often cited as the death-blow to nitrogen tire inflation. Since Consumer Reports found the benefits to be negligible, the benefits must be negligible and the whole thing must be a scam to make more money. However, we’ve poked holes into how this study was conducted, and we think that the service ought to at least be tested again in a manner that actually evaluates how the tires perform and maintain tire pressure while being used on the roads, not just sitting idle outside for a whole year.

Something that many naysayers miss is Consumer Reports’ conclusion of their study, which reads:

Bottom line: Overall, consumers can use nitrogen and might enjoy the slight improvement in air retention provided, but it’s not a substitute for regular inflation checks.

Essentially, they don’t discredit the use of nitrogen. They simply say that it’s not a substitute for regular tire pressure checks, which is something that the nitrogen tire inflation industry and its supporters have been saying this whole time. Naysayers ought not to discredit the practice so quickly based on one study, especially since the study has its flaws and that the researchers did not conclude that the practice was bogus.

nitrogen tire inflationEven with mass communication as powerful as the Internet, it’s still possible (and perhaps much easier than ever) to disseminate misinformation and untruths. The topic of nitrogen tire inflation is no exception to this, and we’re committed to busting myths and eliminating the untruths that circulate online, even if we have to bust certain myths more than once and really drive home a few key concepts. Here are some old, and new, untruths about nitrogen-filled tires, and what the truth really is.

If you have a nitrogen-filled tire that needs air and you top off with regular air, you’ve negated any of the benefits you had gained. (Because so few places have nitrogen equipment, you’ll often find yourself seeking out a regular air pump at a gas station.)

Absolutely not true. It’s not as if topping off an air-filled tire with nitrogen benefits your tire like a tire filled 100 percent with nitrogen. Granted, topping off a nitrogen-filled tire with air isn’t the best, but you don’t negate all the benefits. Just because it’s harder to top off with nitrogen doesn’t mean that nitrogen tire inflation isn’t worthwhile.

A while ago, I replaced the air in my tires with nitrogen at a cost of $20. Now I’ve noticed that I’m getting about 40 miles less per tank of gas. Can nitrogen cause a drop in gas mileage?

Anyone who says that with nitrogen tire inflation, you don’t have to worry about tire pressure ever again, is lying. Nitrogen tire inflation maintains proper tire pressure for a longer period of time, but it doesn’t keep your tires properly inflated forever. It’s not the nitrogen that ruins your gas mileage, its the underinflated tires. You still have to check them regularly, even if it’s just to make sure you don’t have a leak. As the myth says, tires that are underinflated will diminish your fuel efficiency.

The other argument for nitrogen over air is that oxygen within normal air causes ‘oxidation’ within the tire. However, I haven’t seen any concrete evidence as to what oxidation really is or why its such a bad thing.

Oxidation is the interaction between oxygen molecules and other elements. It’s what causes an apple to turn brown, unopened food to spoil after a long period of time on the shelf, metal to rust, and rubber (such as the rubber in tires) to deteriorate. If any of those examples don’t count as concrete evidence, than I don’t know what does. Just because we typically call it rust or rotting doesn’t mean that oxidation doesn’t exist or is some fancy scientific principle that’s too difficult for normal people to understand.

The advantage of nitrogen being more stable and less prone to changes in pressure due to heat in the tires seems of little benefit to average drivers.

Not true. Sure, normal drivers aren’t driving under the extreme conditions that NASCAR drivers and airplane pilots do. Both use nitrogen-filled tires on a regular basis, and are right to do so because there are much more extreme temperature changes than in daily life. However, just because the temperature changes aren’t extreme doesn’t mean that they don’t happen in daily life, and it doesn’t mean that those less extreme changes don’t make a difference in handling and tire pressure. Since nitrogen better handles these changes, it means that a driver will get more accurate readings of his/her tire pressure, and will less likely overinflate/underinflate their tires unnecessarily. More stability also means a safer tire, one that is less likely to suffer a blowout.

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