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How Maximum Tire Pressure and Saving Gas are Related

On January 10, 2013, in Fuel Efficiency, Proper Tire Pressure, by allisonmreilly
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saving gas and maximum tire pressureWe came across two articles about gas saving myths and gas saving tips, and both article recommended that keeping tires as maximum tire pressure is best for fuel efficiency. Although the articles are correct that overinflation and underinflation are harmful, the idea of maximum tire pressure could be misleading. Here’s why:

The Number on the Sidewall

Many mistakenly believe that the number on the sidewall is the recommended tire pressure for the tire. This is false, as the number is the maximum tire pressure the tire can handle, according to the manufacturer. For the recommended tire inflation pressure, check the label located on the driver’s door or the owner’s manual. This is why the idea of keeping tires at maximum tire pressure can be misleading. Maximum tire pressure is overinflation, as it’s not recommended. The pressure label on the tire also does not indicate the manufacturer’s recommended tire inflation pressure, nor does it indicate the proper air pressure based on the vehicle the tire is mounted on.

If You Have Road Noise or an Extra Bumpy Ride, Your Tires aren’t at Proper Tire Pressure

The articles also state that with maximum tire pressure, you’ll have a bumpier ride and a bit more road noise, but you’ll also have the improved fuel efficiency so it’s a nice trade-off. This is also not true, because bumps and noise means that your tires aren’t at their proper tire pressure, so you are probably wasting gas instead of operating at top fuel efficiency. This is because tires that are over- or underinflated do not have the right contact with the road, destroying your tires and ruining your fuel inefficiency. The picture below demonstrates this phenomenon, where it’s obvious to see that without proper tire pressure, no aspect of your tires or your driving (which includes fuel efficiency, handling, tire life etc.) is at its best.

overinflated tires

What’s the Right Tire Pressure for Optimum Fuel Efficiency?

The proper tire pressure is what’s recommended, which as can be found in the owner’s manual or on the driver’s door (as previously stated). Do not go by the sidewall or your friend’s recommendation or what you feel is the right tire pressure. It’s also important to check your tire pressure regularly, and to make those checks when your tires are cool, so not right after you’ve come home and certainly not at the air pump at the gas station. You will have a more accurate reading when your tires are cool.

The best way to maintain proper tire pressure and to have optimum fuel efficiency is with nitrogen tire inflation. Nitrogen-filled tires maintain proper tire pressure for longer periods of time, which means you get that fuel efficiency boost without that bumpy ride and without overinflating your tires. Of course, nitrogen-filled tires still need to have their pressure checked regularly. Sure, they may take longer to lose their pressure, but that doesn’t mean that they never, ever lose it.

What’s the True Tire Pressure/Gas Saving Tip?

The accurate gas saving tip is to make sure that your tires are at proper tire pressure, the one that is recommended in the owner’s manual or on the driver’s door. You don’t ever want to be at maximum tire pressure, and you certainly don’t want to be using tires that are worn. Also, make it a habit to check your tire pressure regularly, and get nitrogen-filled tires if you can.

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Some of the Wackiest Arguments Against Nitrogen Tire Inflation

On December 13, 2012, in Nitrogen in Tires Myths, Nitrogen Tire Inflation, Proper Tire Pressure, by allisonmreilly
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nitrogen tire inflationWe’ve done out best to bust nitrogen tire inflation myths and other arguments against the practice. Some of these arguments are understandable and logical, but others are just plain wacky. These wacky arguments skew the discussion because some people may believe them, leading them to thinking nitrogen tire inflation is a scam because nitrogen tire dealers and providers are making wild claims about the practice. Not only are dealers and providers not making these claims (we can’t speak for the mechanic or the salesperson, but we assure that those who sell the equipment aren’t making these claims), but these claims are just wrong. Here are a few them that we found and would like to bust right now:

As for moisture, changes in humidity affect tire performance two ways. First, the density of humid air fluctuates more with temperature than that of dry air, so removing humidity can keep your tire pressure more consistent, especially when the temperature climbs over 100 degrees Fahrenheit. That may be a legitimate concern in Formula One racing, but it’s not much of an issue if you’re just tooling around town. – The Straight Dope

The density of humid air has nothing to do with tire performance. Humid air is bad for your tires because it is humid, because the water vapor is very susceptible to temperature changes and causes the tire pressure to fluctuate. This also happens at temperatures below 100 degrees Fahrenheit because as you drive, you heat up the tires, no matter what the temperature is on the outside. They’re moving, there’s friction, and all that creates heat. All this is a concern if you’re just tooling around town, because tooling around town creates heat as well, and the water vapor in your tires is still reacting.

Another claim I’ve seen is that since nitrogen is slightly lighter than air, you’ll save weight and get better performance. However, we’re talking about a weight difference of less than 4 percent of the gas in the tire – in other words, a difference of less than an ounce for most vehicles. – Also The Straight Dope

We have no idea who said this, but the better performance from nitrogen doesn’t come from saving weight. It comes from the fact that nitrogen maintains proper tire pressure for a longer period of time, and its the proper tire pressure that creates better performance and handling.

The argument for using Nitrogen in your car tires is this: Air and Nitrogen would compress at different rates depending on temperature, with air being more squishy than Nitrogen, and that would cause your tires’ pressure to vary more with air than with Nitrogen. – Scienceblogs.com

More squishy? What does that even mean? Just because this argument is coming from a science blog doesn’t meant that it’s scientifically sound.

Proper inflation is the real issue. Under-inflated tires reduce gas mileage. They flatten out, creating more surface area and thus adding friction, which makes the engine work harder. The extra friction, and resulting heat, also increases the chance of a blowout. A properly inflated tire is always safer and more efficient than under-inflated shoes (unless you’re driving across a sand dune). – The Truth about Cars

If only it were this simple. Since air-filled tires are much more susceptible to temperature changes, there are chances for an inaccurate reading when checking the tire pressure of an air-filled tire. For example, if a consumer stops at a gas station after spending some time running errands and driving around, and decides to check their tire pressure, it’s likely that they’ll get a reading that is higher than what the tire pressure really is. The reason is the tires have been heated up from the previous driving,

This could mean that the consumer gets a reading that says their tire pressure is fine, or is too high, and will do nothing about a tire that’s really low or will make it low by releasing pressure to compensate for the high reading. This is why it’s recommended to check tire pressure when the tires a cool, such as before starting the car or after being parked for a few hours. Since tire pressure ought to be checked when the tires are cool, this means that tires would need to be refilled at home with an at-home air compressor (since most people would have to drive to the gas station to get to their air compressor, heating up the tires and ruining the reading).

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Even More Untruths about Inflating Your Tires with Nitrogen

On November 1, 2012, in Nitrogen in Tires Myths, Nitrogen Tire Inflation, by allisonmreilly
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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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The Advantages and Disadvantages of Nitrogen Tire Inflation

On October 18, 2012, in Nitrogen in Tires Myths, Nitrogen Tire Inflation, by allisonmreilly
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advantages of nitrogen tire inflationWe’ve touted a lot of nitrogen tire inflation benefits, and rebutted our share of nitrogen tire inflation myths. Although we support the practice of nitrogen-filled tires, it’s not the most perfect thing in the world, and it has its advantages as well as its disadvantages. It seems that a lot of folks are either on one side or the other, without strong consideration of the arguments on both sides. Here’s a list of those advantages and disadvantages of nitrogen tire inflation, so people can make an informed decision about the practice, instead of relying a collection of conflicting resources.

Nitrogen Tire Inflation Advantages

  • Nitrogen tire inflation improves fuel efficiency by maintaining proper tire pressure for a longer period of time. Proper tire pressure improves fuel efficiency anywhere from three to six percent. That might not seem like a lot, but with gas prices the way that they are, the less money we can throw away, the better.
  • Nitrogen-filled tires have a longer life because they don’t have the corrosive properties that come with air-filled tires, mainly the oxygen and the water vapor. Not only does oxidation ruin the rubber in the tire, but both the oxidation and the water vapor can affect the aluminum and steel wheels on the inside.
  • Nitrogen-filled tires create a smoother, safer ride. With underinflated tires, there is less contact area between the tire and the road surface. This leads to reduced steering control and a greater potential for blowouts.
  • Nitrogen-filled tires are a way to go green. Over 300 million tires are disposed of every year, and nitrogen tire inflation can reduce this amount by 30%. Also consider the fuel savings as another way to go green and to cut down on carbon emissions.

Nitrogen Tire Inflation Disadvantages

  • Nitrogen doesn’t make a difference if you run over a nail. Some will argue that because it doesn’t matter what’s in your tire when it has a hole and its going flat, that there’s no reason for nitrogen tire inflation. No, nitrogen won’t help you in this case, and we don’t know of any nitrogen tire inflation company or dealer (certainly not us) who will say that nitrogen will negate the consequences of running over a nail.
  • Nitrogen-filled tires won’t help you in a fiery crash, and once again, no legitimate nitrogen tire inflation company or dealer will say otherwise. We only mention this disadvantage because it was mentioned in an article that said nitrogen-filled tires were a scam, and might believe that dealers are using this argument as a selling point. The author might have been confusing an advantage of nitrogen, where tires will run cooler and are less susceptible to temperature changes (so there’s less chance of a blowout or of inaccurate readings when topping them off). However, in a fiery crash, nitrogen-filled tires won’t mean all that much.
  • Nitrogen tire inflation doesn’t eliminate the need for regular pressure checks and tire maintenance, nor will they never ever lose pressure again. With nitrogen, you might not need to top them off so much, but you don’t fill up your tires with nitrogen and forget about them. No nitrogen company or dealer will ever suggest that nitrogen tire inflation is a replacement for checking your tire pressure, or that your tires will stay inflated at proper tire pressure forever and ever.

nitrogen tire inflation myths paper

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A Rebuttal to Nitrogen Tire Inflation Scams and Myths

On October 4, 2012, in Nitrogen in Tires Myths, Nitrogen Tire Inflation, Proper Tire Pressure, by allisonmreilly
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nitrogen in tiresToday, we will call foul on an article from 2008. Carl Feagans in a Hot Cup of Joe argues that nitrogen tire inflation is a scam and not worth it for general consumers. Although we do think that the benefit of nitrogen tires is best seen in managed fleets, that doesn’t mean that the whole practice is a scam and that there isn’t any benefit at all.

Nitrogen-Filled Tires Maintain Proper Tire Pressure Longer

Feagans’ biggest argument in claiming nitrogen tire inflation is a scam is that nitrogen actually effuses faster from a tire than oxygen. He points out that what’s used in the tires are the diatomic molecules (N2 and O2), not just the element. Based on Graham’s law of effusion, nitrogen would leak faster than oxygen.

The science in Feagans’ post is accurate. However, it doesn’t apply because the argument discusses nitrogen and oxygen, while with nitrogen tire inflation, the discussion is between nitrogen and regular air. Regular air is much more than oxygen, and no one fills their tires with pure oxygen. Therefore, Feagans’ argument doesn’t disprove the value of nitrogen tire inflation. Feagans wanted a non-nitrogen tire industry study that found nitrogen-filled tires lasting longer than air-filled ones. Well, Ford conducted a study in 2004, and not only found that the nitrogen tires did last longer, but that oxidation takes places from the inside out. And Ford isn’t the only one that supports the practice: Michelin and Firestone also think that nitrogen tire inflation is a good idea. Popular Mechanics also said the same thing in 2009.

Oxygen or Nitrogen: Which Is It?

Yes, air is 78% nitrogen and 21% oxygen. Nitrogen tire naysayers love to quote these numbers as the reason why nitrogen tire inflation is a scam as if a 21 percent jump isn’t good enough. Would we argue that with anything else in life? (You’re 21% increase in sales in no good. Get that up to 33% and we’ll be happy. A 21% discount isn’t enough. I need a 50% discount.)

Anyway, we digress. Feagans is no different in quoting these numbers. Naysayers also, even when quoting the 78%, also love to downplay the power of oxygen while saying that 78% nitrogen is somehow good enough (even though the nitrogen doesn’t do anything. That’s why this whole thing is a scam). One of the consequences of regular air is oxidation, and Feagans asks why oxidation doesn’t take place on the outside and why the nitrogen dealers are only worried about oxidation on the inside. The biggest reason is that oxygen is a very reactive element, and affects more than just the tire. The oxygen will also corrode the aluminum and steel wheels, causing additional problems to your vehicle. It’s not just the rubber we’re worried about.

Oxygen is not only reactive with other elements, it’s also very reactive to temperature. The airline industry and NASCAR use nitrogen-filled tires because their tires can run so hot that an air-filled tire will suffer a blowout under most of their conditions. Yes,  nitrogen is less volatile. No, it doesn’t matter if you’re in a fiery crash. However, your tires will run cooler with nitrogen, so they are better protected against a blowout, which does happen to regular consumers and managed fleets.

Nitrogen Tire Inflation is No Scam!

Even so, it is not a replacement for checking your tire pressure regularly and making sure you are maintaining proper tire pressure at all times. Flats still happen, and even though nitrogen maintains proper tire pressure longer, it still does leak over time. There is always a better way to do things, even simple things like keeping your tires inflated. Nitrogen is that better way, until someone creates a tire that doesn’t leak and doesn’t need to be topped off ever again.

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Guess What? Air Isn’t Free Anymore. Nitrogen Tires a Better Deal.

On August 9, 2012, in Nitrogen Tire Inflation, Proper Tire Pressure, by allisonmreilly
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compressed air nitrogen tire inflationOne of the biggest gripes about nitrogen tire inflation is that air is free, so why pay for something that you can get for free? However, it turns out that’s an outdated notion, as in some places, consumers have to pay anywhere from $.50 to $2.00 just to use the air compressor. Granted, in states like California, consumers can get air for free if they buy gas, but in most states, such a law doesn’t exist. This means, in most places, this gripe about nitrogen tire inflation is completely moot.

Since in most places you have to pay for both compressed air and nitrogen tire inflation, then consider it a comparison of product instead of a comparison on price. Much like a comparison of cheap shoes versus expensive shoes, or a cheap restaurant versus an expensive restaurant, you’re looking at much more than the dollars. You then have to consider if paying a little bit more for nitrogen tires provides more benefit and value than regular air.

But, Air is Already 78% Nitrogen

Yes, but that’s one of the biggest misunderstandings of nitrogen tires. It’s presumed that nitrogen is used because nitrogen is so special. However, the main reason why nitrogen is used is because the other 22% of air is so harmful for tires, primarily the oxygen and the water vapor. Both oxygen and water vapor are much more receptive to temperature changes, causing tire pressure to fluctuate. This means, if you don’t check your tire pressure when your tires are cool, such as when you pull into a gas station to fill up, you could be getting an inaccurate reading of your tire pressure. So, you’re filling up and you think you might be adding needed pressure, when in fact you could be overinflating them. On the other hand, if you do a reading and see that your tire is already overinflated, you could be releasing tire pressure from a tire that was already at proper tire pressure. Whether your tire is overinflated or underinflated, both conditions negatively impact fuel efficiency and tire life.

 Checking Tire Pressure Regularly will Do the Same Thing

We certainly don’t recommend nitrogen tire inflation as a substitute for checking tire pressure regularly, but when you consider that 85% of people don’t know how to properly inflate their tires, what good will regular tire pressure checks do for most people (unless they get it done at an auto service station)? At least with nitrogen tires, proper tire pressure is maintained for a longer period time, and  pressure checks can be done at regular maintenance checks with little worry. With nitrogen tires, consumers will have one less thing to worry about, which is a nice thing in our incredibly busy lives. Unless skeptics are going to start teaching people how to properly inflate their tires instead of complaining about how nitrogen tire inflation is a scam, then they aren’t solving for the fact that 44 million people in the United States are driving on at least one underinflated tire.

Nitrogen-Filled Tires are a Better Product

When it comes down to it, nitrogen tire inflation offers a much better product than a tire filled with compressed air. Sure, it costs more, but there are a lot of products that cost more and are much better than their cheaper counterparts. Nitrogen tire inflation provides tires that will maintain proper tire pressure for a longer period of time and will help those people who, for whatever reason, don’t check their tire pressure regularly or don’t know how to properly inflate their tires. By going to a professional or to an auto service shop that offers nitrogen tire inflation, you are sure to get someone who knows what they are doing and can provide you this better product correctly.

DU8MHR6BVP86

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Two MORE Nitrogen Tire Inflation Myths Busted

On September 8, 2011, in Nitrogen in Tires Myths, Nitrogen Tire Inflation, by allisonmreilly
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nitrogen tire inflation mythsA few weeks ago, we busted two myths about nitrogen tire inflation. Today, we are busting two more (there are quite a bit of myths out there). Since the practice of putting nitrogen in your tires is still new, there’s still a lot of possibility of rumor and falsehoods permeating the scene. Which means, some of us out there need to accept the responsibility of disproving those rumors and dispelling those falsehoods. Here are two more myths, busted:

1) TIRES FILLED WITH NITROGEN ARE NOT AFFECTED BY TEMPERATURE

This may seem like the case, since that’s one of the reasons why NASCAR and the airline industry use this practice. After all, since both race cars and airplanes travel at fast speeds, the ability for nitrogen-filled tires to retain those speeds without bursting makes it seem like nitrogen isn’t affected by temperature. However, nitrogen and compressed air respond to changes in ambient temperature in a similar manner, a 1.9% change of pressure for every 10F change in temperature. The difference lies in the water present in conventional compressed air, where dew points (the dew point temperature is the temperature at which the air can no longer hold all of its water vapor, and some of the water vapor must condense into liquid water. The dew point is always lower than, or equal to the air temperature) can be as high as 70F, compared with -40F+ for nitrogen. As temperature increases, liquid water vaporizes to become a gas and its volume expands causing tire pressure to be higher than that of nitrogen, which goes into the tire as a dry gas. So, the presence of water in a tire contributes to wild pressure variations as temperatures changes. The bottom line is that you will still see pressure changes with nitrogen, but the pressure doesn’t fluctuate as much as it does with compressed air.

2. LOOK AT THE PERIODIC TABLE. NITROGEN MOLECULES ARE NOT LARGER THAN OXYGEN MOLECULES

The periodic table is separated based on molecular weight, not molecular size. That being said, diatomic nitrogen (N2) is slightly larger than diatomic oxygen (O2), and this difference allows it to fit through the relatively tight passage ways between polymer chains in the rubber. The difference in size between O2 and N2 is almost infinitesimal, only about 0.3 x 1o raised to the -10 meters, or 0.00000000003 meters. Thus, diatomic oxygen permeates approximately three to four times faster than diatomic nitrogen through a typical rubber, such as what’s used in tires. Just because oxygen is heavier than nitrogen, doesn’t necessarily mean that it’s also larger than nitrogen.

Overall, nitrogen tire inflation is an excellent practice that will make your tires and driving safer and cheaper in the long run. Since this is something that is still new, there’s going to be plenty of people who don’t believe in the benefits and aren’t going to find this worthwhile. However, many have found this practice to be beneficial and to make a difference with their cars and with their wallets.

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