I passed on the link to the owner of NitroFill. He read through everyone's comments and sent me this reply.

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Elliot,

Thanks for forwarding the comments from your fellow hybrid owners. To address the concerns raised in the limited number of comments you forwarded:

It is true that nitrogen, viewed exclusively as an inflation medium, will not have a measurable, to a practical standard, positive impact on fuel economy. The main benefit of nitrogen inflation, viewed in this narrow capacity, is its quality to dramatically retard the normal permeation process.

Tires typically lose 1-3 pounds per square inch of pressure per month through natural permeation. By studying a permeation table you will note that the loss is primarily oxygen and water vapor. Tires inflated with nitrogen, at a high purity such as provided by all NitroFill dealers - at least 95% IN the serviced tire, will typically lose no pressure in the same duration. And therein lies the benefit: Adequate inflation has a dramatic impact on rolling resistance and hence fuel economy. Because only a very small percentage of the population regularly monitors their tire inflation the benefits of nitrogen inflation, especially with the ever expanding recommended new vehicle service intervals, does have a substantial impact on fuel economy. For proactive enthusiasts that are vigilant regarding their tire inflation, these benefits are obviously reduced.

Inflation value retention is only one benefit of nitrogen inflation. Nitrogen inflated tires run cooler and maintain a more constant pressure and are therefore prone to last longer and fail less often. Perhaps the most important benefits, however, are those provided from nitrogen's characteristics as an oxygen free, moisture free inert gas. As stated above, the first substances to permeate through a tire filled with compressed air are water and oxygen: the 2 key components of oxidation and corrosion. These substances are "pushed" through the tire under 30 psi+ pressure damaging the steel and rubber components of the tire and corroding the wheel and related hardware. Because nitrogen, properly administered, is oxygen free, oxidation is eliminated increasing tire life and safety. Furthermore, because nitrogen is moisture free, it creates a perfect environment for Tire Pressure Monitoring devices.

I hope this helps address your concerns.

Jay Lighter
President
Kreska Technologies, Inc.
NitroFill
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My HCH2 is the 5th vehicle where I am using Nitrogen in the tires. My personal experience has been very, very favorable.

 

What crappy tires does he have that do that? Mine don't.

 

It certainly happens on our bicycle tires (MTB and road bikes), and although I haven't had my Ford Escape Hybrid very long (the first car I've checked tire pressures on more than once every couple months or when it "feels" low), all of my tires went from 40psi to 38.5 psi in one month's time. And weather wasn't a factor in the decline, as temperatures had risen over that month not dropped.

BTW: My comments are only referring to traditionally filled tires. I have no experience or position on Nitrogen-filled tires of any type.

 

This guy is still BSing us. I seriously doubt that oxygen will make the tires run at a different temperature than nitrogen. And, if anything, moisture content would help the tires run cooler. If the water is in liquid form, it would take energy to convert it from liquid to gas without raising the temperature. Once the water is in gas phase, it has a much higher heat capacity than oxygen or nitrogen. Applying the same amount of energy will cause water vapor to go up less in temperature than oxygen or nitrogen.

As for permeation, it is a function of both the pressure differential of the particular gas (inside vs. outside of tire) and the permeability of the particular gas in the rubber. Oxygen does have a higher permeability than nitrogen through natural rubber (about 2.5 times), but there is about 4 times more nitrogen than oxygen in normal filled tires. (These numbers could be different for the rubber used in tires.) This means that more nitrogen would be lost. If you increase the nitrogen and reduce the oxygen, you will reduce the oxygen that is lost. But you will also increase the nitrogen that is lost. Either way, I wonder if permeation through the rubber is even the main mechanism for pressure loss. I would guess that it is through seals.

If oxygen permeation is as bad as he says, the tires are becoming naturally oxygen deficient over time. Keep in mind, they are only shooting for 95% nitrogen. I bet the other 5% is mostly oxygen.

Anyway, that's my two cents.

 

I hear if you put 100% helium in your tires it reduces the unsprung weight and causes your car to float right over the road

 

It will drop your weight by maybe a pound. That's just the edge some of these hypermilers are looking for. However, helium really will leak out fast.

 

Helium... hmmm.

How big of a 'blimp' style balloon would one need, tied to the roof of the vehicle to lighten the load, to increase fuel economy?

 

Blimp wouldn't work... too much wind resistance!

 

The issue with moisture in a tire is condensation and evaportion, not heat capacity. If the tire cools a lot on a chilly night, the water vapor will condense, lowering the pressure inside the tire much more than if the air was dry. Driving on a hot road will cause any liquid water to evaporate inside the tire, raising the pressure much more than if the air was dry.

 

I am very aware of the issues. Look at post number #16 in this forum. There are multiple issues. One of them is pressure variation which can be affected by moisture content. This is where the condensation and evaporation come in to play. During evaporation, the water goes from liquid (very small volume) to gas (very large volume). This will increase the pressure.

Another of their claims was that having pure nitrogen will make the tires run cooler. The way I see it, just the opposite would be true. (I believe these effects would be very small.) Anyway, just to prove a point, I brought up all the effects I could think of for having oxygen and water in the tires. When you start driving your vehicle, you will be adding energy to the tires (through friction and such). If there is condensed water in the tires, this energy will go towards evaporating this liquid. This process sucks up energy, but it does not raise the temperature. (It will keep the tire cooler.) Also, once the water is in gas phase (evaporated), it will heat more slowly than oxygen or nitrogen (assuming you are adding the same amount of energy). This is why I brought up the heat capacity of water. The heat capacity of water is higher than that of nitrogen or oxygen.

I'm really not sure what you think was wrong about what I said. I'm quite sure it is accurate as this is an area in which I am well schooled.

Mr. Kite, Ph.D. (Physical Chemistry)