Nitrogen Tire Inflation: Why It's Better Than Air
Uploaded by Mason Costa on October 26, 2011 at 12:56 PM
Nitrogen is already 78% of your tire's inflation, why not go for more?
Contents
- Decreased Pressure Loss
- Non-Corrosive
- Increased Gas Mileage
- Wrap Up
For those of you that slept through Chemistry in high school, it's time for a pop quiz. What is the most abundant element present in the air we breathe? Oxygen? Hydrogen? Lead? No, none of those, it's Nitrogen. This doesn't have a heck of a lot of bearing on the article today, other than to say that Nitrogen is everywhere. You breathe it, you even use it in your car's tires. That's right, you're not filling your tires with pure oxygen, it's just a compressed form of the air we all enjoy; which kind of makes it silly to pay for, doesn't it? The air we breathe and use in tires is a mixture of about 78% Nitrogen, 21% Oxygen and 1% other elements. As the title suggests, I want to discuss inflating your tires with pure nitrogen instead of the usual air mixture
People are still hesitant to pump their tires full of old number 7, nitrogen's number on the periodic table. First of all, the people that feel silly paying for air aren't going to pay the $20 or $30 or whatever their local shop charges for a nitrogen fix. Maybe after reading this, those people will change their mind. Nitrogen inflated tires may save you substantial money in the long run. They extend the life of tires, increase gas mileage, and they are great for people that don't want to do the normal maintenance required of your vehicle.
Thanks to the cold, many of us need to fill up our tires
Decreased Pressure Loss
It's starting to get colder in many parts of the country. Leaves are changing colors, sweaters and hoodies are making their triumphant returns and tires are starting to go flat. That's right, cold air decreases air pressure in tires. This is due to a few things. First, the cold slows down subatomic motion and actually causes molecules to shrink a bit. So all of the molecules in your tire are actually shrinking; to the tune of losing 1 PSI of pressure for every 10 degrees. For the curious minds out there, it works the opposite way when the temperature rises. Unfortunately, nitrogen has to abide by the laws of physics, so a nitrogen filled tire will still suffer from psi loss in the winter. The other reason for pressure loss involves looking more closely at your tires. If you could look at them under a high powered microscope, you'd see rubber isn't a solid sheet, it's more like thousands of strands clumped together. This makes permeation by the gas inside your tires rather easy. By the way, if you slept through Chemistry, it's time for some schooling. Oxygen is a highly active and "fast" gas. It is quite apt to seeking out more partners to react with, and will escape through the tiny cracks in the tires to find them. Nitrogen, on the other hand, is a "slow", inactive gas. This means Nitrogen doesn't really play well with others and doesn't seek out new dance partners. In other words, nitrogen is much less likely to permeate the tires walls and seek freedom.
Another reason nitrogen rich tires don't suffer from the same amounts of pressure loss is due to nitrogen's relative disinterest in reacting with hydrogen. As almost everyone on the planet knows, oxygen bonds with hydrogen molecules to form water. Water doesn't exert pressure on your tires unless you filled the tire entirely with water. Otherwise, it's just going to sit there and pool up at the bottom of the tire. This obviously leads to reduced pressure, and the need to fill your tires up more often. Nitrogen is quite uninterested in hydrogen. It's perfectly happy doing it's job and leaving hydrogen alone.
Non-Corrosive
If you've not worked as a tire tech or done some research, you may not be aware that there is a good deal of metal in your tires. Tires utilize steel belts, metal reinforced sidewalls and a metal rim called the bead. The bead is the lip of the tire makes contact with the wheel. Metal does not like to play with water and oxygen. Water will cause metals to rust and weaken, and oxygen will cause metal to oxidize. Needless to say, this is not good for your tires. If the bead were to lose structural integrity, your tire could fail to make a tight seal with the wheel, causing rapid pressure loss. If the belts or sidewall corrode or rust, your tires become incredibly unsafe to drive on. With nitrogen, these worries are significantly lessened. Nitrogen doesn't react with hydrogen, so you don't have to worry about it forming water. Nitrogen also doesn't cause corrosion in the metal aspects of your tire.
The non-corrosive benefits of nitrogen are particularly useful to people that don't drive there car very often. None of the bad things I just mentioned happen over night. Usually you'll notice some signs of degradation and can act accordingly. But what if you only drive the car every so often. Maybe you've gone out of town for a few weeks or more. Your tire is just sitting there, acting as a petri dish for hydrogen and oxygen to mix, and allowing the water and oxygen to react with the metal. You could potentially come home to a vehicle sitting on flats, or more likely, a car that is slightly less safe to drive.
Increased Gas Mileage
This one is kind of an ancillary benefit of having more consistent tire pressure, but with the gas prices today, people are looking for these savings everywhere. If your tires have the proper level of pressure in them, they will actually reduce friction from the road while you're driving. This reduction in friction results in an easier time moving your car, and less gas is required to do it. Don't believe me? Go outside and get a wheel barrow. Put a few pounds of something in it; have a kid ride in it or move some dirt. Inflate the tire properly and push it 50 feet. Then deflate the tire to about 75% of it's normal amount and push it back. It was harder wasn't it? Still not satisfied, take about 25% more of the original amount out. Now we're down to a half inflated tire, which is by no means abnormal to see on the road. Now do the 50 foot route again. If you say that wasn't more difficult, you are obviously lying to yourself. The moral of the story is that the more air in a tire, to an extent, the better it is for fuel economy.
In the 2008 election cycle, the topic of offshore drilling was fairly prevalent. At one point, now president Obama said that proper tire inflation and tune up could save as much oil as offshore drilling would produce. The McCain campaign laughed it off and mocked the assertion. While it may not save enough to make offshore drilling less appealing to some, the fact is proper tire inflation can improve fuel economy for the average driver by 3.3%. Extrapolating this to the entire driving population the DOE estimates proper tire inflation could save the country over 3 million gallon of gas per day. Whether it will save America from energy dependence or not, that is a lot of gas we're just wasting every day. If you're interested in the statements above, here's the fact check of President Obama's statements in that debate: USA Today Fact Check.
Wrap Up
As we've seen, nitrogen is definitely an improvement over traditional air inflated tires. Whether it's worth the expense is determined on a situation by situation basis. If you buy new tires and the shop will inflate them with nitrogen for you at no cost, then definitely do it. If you see somewhere that will do it for under $5 or so a tire, it should still save you money, though I'd be a bit weary of that. Anything over $5 a tire or if you have get some sort of service contract, I'd say you should pass. The fact of the matter with nitrogen tires is that the biggest benefit is you don't really have to do the routine maintenance for your tires. If you are the type to check your tires regularly, then nitrogen probably won't save you much. But if you're like me and don't notice your tire is low on air until someone stops you on I-285 in rush hour traffic to tell you your tire is dangerously low, then this may be good for you. Nitrogen inflation won't ever hurt, but I don't think it's worth more than about $20 for the entire deal. If it's more than that, I suggest just investing in a good pressure gauge and checking your tires once a week or so. Thanks for reading and keep those tires inflated, either with air or nitrogen.
