Just to muddy up the water, I fill my tires with CO2. Its a much larger molecule than either N2 or O2, so it doesn't leak. It also will help extinguish a fire in the event of a major accident. Ok, perhaps I really just use CO2 because I have the setup left over from the hobby and vehicle the Prius replaced. Its much easier to take a 10# CO2 tank out to the car to top of the tires than dealing with a slow and noisy air compressor. I could fill the tires from flat to full in a few blinks of the eye, amazing what ~850psi on instant reserve can do.
<div class='quotetop'>QUOTE(PriusDiver @ Nov 5 2007, 04:58 PM) [snapback]535180[/snapback]</div> Have you considered Helium? It should make your car lighter and result in improved fuel economy. Don't know about fires, though; judging by the Hindenburg, it may have the opposite effect.
<div class='quotetop'>QUOTE(IsrAmeriPrius @ Nov 5 2007, 05:55 PM) [snapback]535201[/snapback]</div> Tongue-in-cheek-ness aside, the Hindenburg was filled with hydrogen, not helium. Helium tends not to burn, being an inert gas and all that.
<div class='quotetop'>QUOTE(PriusDiver @ Nov 5 2007, 07:58 PM) [snapback]535180[/snapback]</div> Ooh, now there's an interesting idea! If just someone could manufacture some device that would connect to the tail pipe and compress the exhaust. Then the compressed exhaust could be stored in a tank in the trunk. Whenever the tires needed a bit of air, you could refill them from the tank. Could fill your friend's and family's tires too. Then the Prius could be "zero emissions"!
I know that when I used to do auto-x and track days w/ the Porsche crowd, some particularly anal guys would use nitrogen. The benefits were invisible, in terms of actual lap times or anything else. I check my tire pressures every few weeks, I don't expect my tires to last more than a few years, and I know the internal air temperature in a tire doesn't get much above 180F in ordinary driving (I have tire temp/pressure sensors on the Porsche). So I don't see how I'll get any discernible benefit from nitrogen fill. I suppose there's no reason to turn it down, but I wouldn't pay 1 cent extra for it.
<div class='quotetop'>QUOTE(PriusDiver @ Nov 6 2007, 10:28 AM) [snapback]535180[/snapback]</div> Trying to think of a hobby where you use CO2. Makes sense though. I have a tyre repair kit with a CO2 bottle or 3 in it, never thought about the big molecules, will they block the valve? :huh:
<div class='quotetop'>QUOTE(John L. @ Nov 6 2007, 04:14 AM) [snapback]535362[/snapback]</div> Nitrogen is an ''inert gas'' and as such, it will not expand when it get warm/ hot. The racing crowd, F1/ nascar uses it to keep the pressure consistent during the race.
<div class='quotetop'>QUOTE(humble @ Nov 6 2007, 07:38 AM) [snapback]535430[/snapback]</div> The inert gases are Helium, Neon, Argon, Krypton, Xenon and oddly, Radon. N2 is chemically quite inert, but is not typically called that. N2 does obey the ideal gas law, as do virtually all gases under typical conditions, so it will expand in a non-fixed volume when it gets warm. It would not surprise me at all that NASCAR does not know this.
I owned an o5 and a 06 pirus and now have an 07 camry hybrid.I have used nitrogen in all 3 and in my wifes 06 corola and my r.v. I have driven all over 14,000 miles in each and lost only 2 lbs.when i first used it i drove 250 miles towards a 400 mile trip and touched my tires and they were cold. I wonder if the people that knock nitrogen have ever used it
<div class='quotetop'>QUOTE(humble @ Nov 6 2007, 09:38 AM) [snapback]535430[/snapback]</div> Nitrogen is not inert, although it does like to stay only with its own. Furthermore, the inert gases, as well as Nitrogen, obey the gas law and expand and contract with temperature. The racing crowd does not use Nitrogen to avoid pressure changes, as that cannot be avoided with any gas, but dry Nitrogen allows them to predict the amount of pressure change, which is very important at the speeds and tire temperatures found in racing. Note that it is imperative that the Nitrogen be dry, otherwise you are back to the same unknowns as ordinary air. Another reason Nitrogen is preferred in racing is that it is quick and easy to fill tires from a tank of Nitrogen. Tom <div class='quotetop'>QUOTE(PriusDiver @ Nov 5 2007, 08:58 PM) [snapback]535180[/snapback]</div> On the other hand, CO2 is a very non-ideal gas. It tends to be quiet squishy, so its volume will change dramatically with temperature and pressure. This is why it is used as a propellant for BB guns, spray cans, paint ball guns, etc. When you squeeze CO2 it turns into a liquid. The pressure in your tires isn't high enough for that at room temperature, but I would wonder how much pressure change you get when it gets cold outside? Tom <div class='quotetop'>QUOTE(duanerw @ Nov 6 2007, 10:47 AM) [snapback]535468[/snapback]</div> Some things are so obvious that they don't need to be tried. I've never taken Arsenic, yet I know it is poisonous. Tom
<div class='quotetop'>QUOTE(zqfmbg @ Nov 5 2007, 11:21 PM) [snapback]535354[/snapback]</div> My bad. How could I forget that due to the Helium Control Act, enacted due to suspicion of Nazi military intents, it was impossible for the Germans to obtain helium and that as a result they resorted to inflating the Hindenburg with volatile hydrogen?
<div class='quotetop'>QUOTE(IsrAmeriPrius @ Nov 6 2007, 05:05 PM) [snapback]535698[/snapback]</div> I thought the Helium Control Act was put in place to limit the number of people talking with high, silly voices. Tom
CO2 turns into liquid ~850psi depending on temperature, of course. I can't imagine the temperature range that the tires experience are dramatic enough to cause that much of a change but I'm too lazy to run the formula right now. The former hobby can be guessed from the video demonstration of CO2 inflation here: http://www.powertank.com/ I sold the gas guzzler that averaged 16mpg on its best of days with a tail wind going down hill. The CO2 is still convenient for bike tires, car tires and feeding the kegerator of home brew
<div class='quotetop'>QUOTE(PriusDiver @ Nov 6 2007, 06:35 PM) [snapback]535765[/snapback]</div> You need to get some really good tires to handle that pressure, but think of the mileage you'll get. :lol: Tom
<div class='quotetop'>QUOTE(duanerw @ Nov 6 2007, 06:47 AM) [snapback]535468[/snapback]</div> What would the nitrogen have to do with the temperature of the tires? The tire heats up due to the flexing of the rubber and the friction with the road, not due to being filled with air or nitrogen. As for less pressure loss, here is Consumer Reports' take on that claimed benefit of nitrogen. They filled identical tires with regular air and with nitrogen, then measured the pressure drop after 1 year. The test started on September 20, 2006 and the final measurements were taken on September 20, 2007. The results show nitrogen does reduce pressure loss over time, but the reduction is only a 1.3 psi difference from air-filled tires. The average loss of air-filled tires was just 3.5 psi from the initial 30 pressure setting. Nitrogen-filled tires lost an average of 2.2 psi from the initial 30 psi setting. More important, all tires lost air pressure regardless of the inflation medium, so consumers should check their tires' air pressure routinely. http://blogs.consumerreports.org/cars/2007...-nitrogen-.html
