Honda Fit Tires..

Please, do us all a favor and go enroll in community college and take a physics class, and ask the professor what is the makeup of the atmosphere we breathe....

....and then come back and tell us your decision on this pressing issue.

Why do you want to turn that off? It sure sounds like you don't know what it does.

Aren't you the helpful one? Lets see, is it: 78 percent nitrogen, 21 percent oxygen, and 1 percent other gases by volume?

This is the first time I've heard of nitrogen in tires. Seems like a more of a marketing tool than a necessity on a Honda Fit.

Two for two on helpful! I guess it, duh, monitors the tire pressure? If you don't know the answer, why reply? Please do us all a favor and stop replying when you don't know the answer.

Or do you know if it can be turned off? Probably not.

The tire pressure monitoring system is federally mandated...and no, you can't turn it off.

Guess I missed that.

Sure enough. Does the TPMS have a dedicated fuse?

Do you have a car with this on it? If a person isn't going to check their tires every so often, is some kind of federally mandated monitoring system going to change that behavior? Can't one just disregard the warning?

Please be patient with me, the last time I bought a car was 1993. I'm not kidding. My 1993 Pathfinder came with air in the tires that I monitor.

There are those that claim it is an advantage.....but it would be so minor, it's not worth the hassle. Most anyone can have a home air compressor, not many have bottled nitrogen (I have it at work where there are advantages to using it in process and storage, but my car tires, not!).

tell us all why you DON'T want a light to come on when a tire has gone significantly below the level of the other tires.

So you know your tires are getting filled with mostly nitrogen already.

And you think getting rid of the oxygen does...what?

As you know by now, it is mandated by federal law.

It monitors the tire pressure. You have yet to tell us why you want to pull the fuse and turn it off.

You have yet to tell us how that system interferes with your life.

"the dealer says". that should have been a clue right at the start - dealers say lots of things which aren't true. in this case, it's called "keep the customer coming back".

air works fine.

you don't want to turn it off - if you get a nail in your tire, it might not flat immediately, but leak faster than your once-a-month schedule and therefore be dangerous, both to you and other road users.

no and yes. tpms has a limit below which it triggers the alarm - it's not an active gauge. you should continue to monitor actual tire pressure in the normal way

It appears to be the latest thing. I looked at a Venza and it's tires were filled with nitrogen. My car buddy says it's a load of hooey since air is mostly nitrogen anyway. Using canned nitrogen instead of the gas station air will keep moisture out of the tires. But I have a little tire compressor that doesn't produce moisture.

OK, I hadn't talked to my car buddy before I posted my questions. He was out of town. Air it is!

Good point. I just thought it was another un-necessary warning light but I see what you're saying. I've read in some other forums that the sensors can be pretty sensitive to minor pressure changes but it's just another light and better safe than sorry.

Thanks for your very helpful reply.

"Elmo P. Shagnasty" wrote in news: snipped-for-privacy@reserved-multicast-range-not-delegated.e xample.com:

eliminates corrosion and oxidation inside the wheel.

Do you think corrosion inside the wheel is a significant problem? I certainly don't.

Most of the places filling tires with "Nitrogen" are using at best 95% nitrogen, not "pure" nitrogen. The main advantage (assuming there is one) is the lack of moisture in the air. However, tires are porus, and I suspect that even if you start out with 95% nitrogen in a few months you'll find that you are closer to atmospheric percentages.

Ed

that's really not an issue.

there are two "advantages" to nitrogen, both of which are highly marginal for normal road cars.

1. better thermal pressure stability. that's why you'll find some racers use it so pressures don't change as much when the rubber's burning, but road cars don't get their rubber anywhere near that hot.

1. tires take longer to lose pressure. air diffuses through rubber, both inwards and outwards. if you fill a tire with 95% nitrogen, at the same time as some nitrogen is diffusing out, oxygen will diffuse back in [look up "partial pressures" on google if you want a detailed explanation] and thus make it seem that the pressure is being maintained slightly better.

but these two are completely irrelevant for normal driving and if the tires are checked regularly.

jim beam wrote in news:0dednalE-_yau_3RnZ2dnUVZ snipped-for-privacy@speakeasy.net:

HOW is oxygen going to "diffuse back in" to a PRESSURIZED tire,from atmospheric pressure? It will NOT.

and Oxygen DOES react with the carbon in tires,and not in any good way.

ok, i acknowledge that this may sound counter-intuitive, but if you know the science, you will understand. that's why i said to look up partial pressures. essentially, just like a high concentration of nitrogen in a tire is seeking to dilute the outside air, the relatively high concentration of oxygen outside the tire is seeking to dilute the nitrogen inside - because the tire is a [slowly] permeable membrane.

not quickly enough to make any practical difference to an ordinary user driving ordinary mileage.

further reading:

Don't you mean "counterdiffusion" rather than "partial pressures"?

Actually, given that a tire is permeable to O2, I believe it will if the partial pressure of O2 inside the tire is less than the partial pressure of O2 outside the tire.

Let's say the tire is inflated with 95% N2 and 5% O2 to 29.4 PSIG (which is 3 atmospheres absolute pressure). The partial pressure of O2 is 3 * .05 * 14.7 = 2.2 PSI. The partial pressure of O2 outside the tire is .21 * 14.7 = 3.1 PSI. Holding all else constant, O2 would diffuse into the tire until the partial pressure of O2 in the tire reaches 3.1 PSI.

the partial pressures provide the diffusion gradients...

Also, I just did a Google search and it seems that tires are much more permeable to O2 than to N2--nearly 4x. Even Consumer Reports found a difference in actual testing. Check out, for example:

However, perhaps unsurprisingly, I see nobody talking about counterdiffusion (N2 diffusing out as O2 diffuses in). This is probably because the gain in O2 pressure is more than offset by the loss in N2 pressure. (The tires are less permeable to N2 but there's a lot more of it and the partial pressure differential is much higher. Still using my example above, the partial pressure of N2 is 3 * .78 * 14.7 = 34.4 PSI. The partial pressure of N2 outside the tire is .78 * 14.7 = 11.5 PSI. This 22.9 PSI differential is about 25 times as large as that for the PPO2s, so even at 1/4 the permeability the N2 pressure loss is about

6 times faster than the O2 gain if I've done all the math right.)

Me? I just use very dry air (scuba breathing air) for tire inflation and check the pressure once in a while. Life is complicated enough without looking for N2 tire fills, and the temperature variations in the Northeast cause greater seasonal pressure differences than an N2 fill would avoid anyway.