2010 Gen III nitrogen in tires

Costco fills your tires with nitrogen when you buy tires from them. So hey, if its free, i'll take it. Otherwise, i'm not paying extra to bleed out my tires and refill with nitrogen.

 

By that definition, the system in the Prius is not good. It only provides a pass/fail for all of the tires.

Tom

 

Not at all true. Oxygen and Nitrogen have almost identical diffusion rates. Based on molecular weight, one would expect Oxygen to have a slightly lower diffusion rate. However, Oxygen has a slightly tighter packing of its atomic structure, so Nitrogen appears to have a tiny advantage. The difference in diffusion rates is so small that only very sensitive laboratory tests can reveal any difference. The practical difference is zero. If you want a lower diffusion rate, use a gas that has a significantly larger molecular structure. Uranium Hexafluoride has very large molecules and is relatively inexpensive given that it is a byproduct of nuclear enrichment. You might want to try that.

This is all silliness anyway. Tires are made to hold gas, not let it through. The gas diffusion rate through tires is low regardless of what common gas you use. Furthermore, as pointed out above, if diffusion occurred at a high rate, your tires would soon reach an equilibrium regardless of whether you started with Oxygen, Nitrogen, or a mix. The gases would diffuse in or out until the partial pressures equalized.

Tom

 

My Toyota dealer suggested nitrogen, and I had it done. The above logic was mentioned and it sounded reasonable to me. But the reason I went for the change was purely financial .... the fill includes free rotations ... I have had three since the change, all at no cost, so I am money ahead.

Now, I cannot state the ride is any better .... or the tread is lasting longer (nitrogen claims) but I can say that the tire pressure has not budged since the nitrogen was added. In our area air is so hard to find now (unlike the old days when SERVICE stations had air .... it is great to check the pressure, find it "right on the mark," and not need to search for air (and when it is found ... it cost).

 

It's good that your tire pressure is holding, but it has nothing to do with "nitronized" tire air.

Tom

 

I can see I can't sneak anything past you.

 

I tried my best to avoid responding to this...redundant...thread. This topic has been discussed multiple times, on this, and every other, car forum I've visited.

Paying extra to have your tires filled with "pure" nitrogen is a total waste of money--unless you have a Formula One car and want the tire pressure to remain as constant as possible as the tire temp increases--from multiple G-force turns.

Does any of this apply to a Prius or most other street cars? No.

 

I tried Uranium Hexafluoride, but it made the tires glow green.

 

Nitrogen and air both obey the Ideal Gas Laws closely enough that there is no difference that is measurable by a tire gauge.

They are called the Gas Laws instead of the Gas Suggestions for a good reason.

 

Even in this application the pressure does not remain more constant as the tire temperature increases. Dry air would have exactly the same characteristics.

What Nitrogen does do is expand in a predictable fashion, but not because of Nitrogen. The key is that the Nitrogen used to fill the race car tires is *dry* Nitrogen. Using a dry gas keeps water vapor out of the tires. Water vapor behaves as a non-ideal gas at common temperatures, which means that tires containing variable amounts of water vapor will exhibit an unpredictable change in pressure as a function of temperature.

Ordinary air would do just as well if it were completely dried. Nitrogen offers a convenient way to store and transport a dry gas, but there is nothing special about Nitrogen's expansion characteristics.

Taking this another step and looking at "nitronized" car tires, the fill gas for this application is only Nitrogen enriched, meaning it has a higher percentage of Nitrogen. It is not the dry Nitrogen used in race cars and airplanes. Even if it were dry, the tire shops use water based lubricants when mounting tires. This completely defeats any supposed advantage.

On a side note, one advantage of Nitrogen is that it does not support combustion. While it's not likely that a tire fire will start on the inside of a tire, when dealing with race cars and airplanes, caution is your friend.

Tom

 

I understand and agree with the water vapor point...but was trying to keep the discussion from getting too complex...and now you've gone and done that!!!

 

I went with the Nitrogen for the safety of not being flammable. That is very important to me since I have had many tires burst into flame spontaneously and some other tires feed fires that were raging in my car. I want to avoid that in my new Prius.

It is a very common problem and this is a good solution to it.

 

What do you do about the oxygen on the outside of the tires?

Tom

 

It's more important to have the straight N2 inside of the tire because it's harder to put out a spontaneous fire on the inside of a tire that it is on the outside.

 

My goodness! You found a flaw in my reasoning. I will have to work on that. I will get back to you. Maybe my dealer will come up with some sort of flame retardant to put on the outside of my tires for a nominal fee of $250 or so.

I am sure lots of people will buy it.

 

who needs tires when your car can fly

 

Air is hard to find in your area? And costs money?

My home and yard is covered with thousands of tons of it. And it is free, except for a few calories for muscle power to operate a floor-standing bicycle pump. Actually, there is a surplus of those calories around my waist anyway, so they really are free.

This is far more convenient than driving somewhere -- anywhere -- to top off the tires, and buying the pump is much cheaper than feeding quarters into machines over the life of the car.

 

As a former Chemistry teacher I've enjoyed this thread and its real world science very much (especially the 'Gas Suggestions'). However, no one has pointed out that helium is the logical gas for tires. It isn't flammable, and it is lighter than air, so the Prius will only weight about 2500 lbs.

Think of the improvement in gas mileage, although of course the car may roll over more easily in an accident!!

 

ok. use He He helium.

 

Seems clear from the posts above that straight nitrogen or oxygen is very dangerous, so I use a custom blend of gasses in my 17" Toyo's. I find that a mix of 78% nitrogen, 21% oxygen and some other trace gases works best. I also keep the same mix ratio in my spare tire. Keeping that ratio and pressure is rather difficult, but at the end of the day it is worth all the effort.