Nitrogen in your tires?
 

Well i went to costco the other days and saw a banner saying Ask us for nitrogen in your your tires or something similar to that. They say it help increase gas mileage and some other stuff which i forget. Nitrogen is a flameable gas right. Does it increase the gas milleage like it says,

Nitrogen is not flamable.

Personally, I'm more in favor of putting helium in the tires. It should have most of the benefits of nitrogen, as well as reducing unsprung weight. ;)

if heard its good stuff, dealers started using this, i think it leaks faster tho im not sure ill read into it

I work at a dealer that sells this. I put it in my tires for free:) it is a little more dense than air so it dont leak out as fast as air. Also it does not change the tire pressure depending on the temp. But our dealer sells it for like 39.99 i would not pay that forit but alot of new cars come with it. Seems to work good would probbably help with track cars once they figure out how to use it since there will be no pressure change.

Nitrogen in tires was SOP in race bikes starting in the late seventies.
No temp expansion and less moisture retention.

The temp expansion in tires is caused by moisture. In order for nitrogen to be effective the tires must be purged to remove moisture. This has been a standard in racing for many years, but I don't see much advantage on the street.

Basically another guy with an idea to make money i know our dealer paid like 10 grand for the setup and people are paying the 39.99 so they are definitily making the money back. Guess it is cool because you dont have to worry about pressure drops in the winter and increase in the summer basically maintance free unless you get a nail or something in your tire. Maybe il grab a flyer from my work and scan it and put it up explains all the crap and makes you want to get it.

Just about everything that was just said is wrong.
The only benefit I have heard about Nitrogen is that it leaks out slower. How much slower, I would say is insignificant. For the most part unless there is a hole in the tire the air is going to stay inside for a very long time. If there is a leak then it does not matter what you put in. I have never seen a tire being used that was low on pressure and did not have a hole in it somewhere.

There air is 78% nitrogen to begin with! The nitrogen they put in your car tires is something like 90-98% nitrogen. (Warning: Prepare for boring math) Your tires are already filled with air at atmospheric pressure (14.7 psi) and if you use the ideal gas law pv=nRT you will be able to work it out to p1/p2 = v1/v2. So after you fill your tires with 32 psi you will find 14.7/(14.7 + 32) = 31 % of the air in the tire is air that was in there before it was filled. So .31 X 78 (%nitrogen in atmospehre) +.69 X 98(%nitrogen in gimmick air for tires) = 91.8 % at the best scenario. So you are looking at a only a 17-18% increase in the nitrogen you already have in your tires. It is possible they could purge the atmospheric air that is already in there but I doubt it.

All air increases in pressure with temperature increases and decreases in temperature with temperature drops. The rule of thumb I have heard is 1 psi for every 10 degrees F.

The moisture from the compressed air in the shop is going to be less than the humidity in the air, unless they are screwing something up. This moisture is going to behave just like gas though.

The arguement is that proper tire pressure will save you money by increasing gas mileage. How much better would it have to be to make it worth $40. It does not make any economic sense unless you own a shop and are just trying to make money off of some suckers. I do not see anything wrong with regular compressed air.

Aside from being a dry gas (which helps if you have steel wheels that might corrode on the inside), the benefit of Nitrogen is reduced thermal expansion. So you'll have somewhat less change in pressure going to/from operating temperature, which racers find to be beneficial.

For a street car with aluminum wheels, it's largely a waste of money. The only people who might save fuel are the idiots who should be slapped in the head with a tire pressure gauge because they don't ever check it.

Dave

Just to let you know you just said everything that we said was wrong but you just restated what we said nitrogen does leak out less and there is less of a pressure change maybe not alot but there is, you explained the same thing just in more words:D

I got it on mine and it seems that my tire pressure is very much the same all the way around on my regular wheels =D I like it.