humbug

I notice that there are tire shops using this which is more stable than oxygen. They use this for airplane tires. Have you tried this and where do you go for this? Costco has it but would not fill my tires since they were not bought through them. Also, where do you go for tire repair and/or replacement for your porsche?

OCBen

More here:

https://rennlist.com/forums/showthre...light=nitrogen

humbug

Thanks Ben. Any recommendation for places for tire repair and/or replacement. I don't quite trust discount tire to handle this. I'm located in San Diego. I have not needed this yet but wanted to be prepared. I did pick up a plug kit just in case I'm stuck out in the middle of nowhere and I could do a temp. fix over just a can of sealant.

uzj100

I've had good luck with America's Tire Co. over the years.

JasonAndreas

Its a gimmick...

FAA regulations require it to reduce fires hazards during landings caused by overheated rims.

“PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES 25.733 (e) For an airplane with a maximum certificated takeoff weight of more than 75,000 pounds, tires mounted on braked wheels must be inflated with dry nitrogen or other gases shown to be inert so that the gas mixture in the tire does not contain oxygen in excess of 5 percent by volume, unless it can be shown that the tire liner material will not produce a volatile gas when heated or that means are provided to prevent tire temperatures from reaching unsafe levels.”


There are no pressure or temperature stability differences between 95% nitrogen that you get at Costco or the 78% you find in the atmosphere.

OCBen

Not really.

Here's an excerpt from a pretty good article on the subject:

To understand the basis for the sudden interest in nitrogen, a little background is in order.

A dry, inert gas, nitrogen's main benefit is its molecular structure; nitrogen molecules are considerably larger than oxygen molecules, so they don't permeate a tire nearly as quickly. Oxygen can pass through an innerliner, belt package and sidewall/tread three to four times faster than nitrogen.

This factor helps maintain proper inflation pressure longer, which means tires run cooler, thereby increasing safety and reducing operating cost.

http://www.tomorrowstechnician.com/tt/tt020532.htm

ltc

I use nitrogen in my son's kart tires for the (racing) reasons given so far.
Could use dry compressed air, but nitrogen is cheap and readily available at welding supply houses ($15/bottle for N2, ~2000 psi).
(I also use it in my Cup car's tires, since it's available in the trailer and provides for a more consistent pressure build up vs temperature)

Crews will also use nitrogen for their air tools/guns; again, dry to help prevet internal corrosion of their tools.....and it's available in the pits already.

JasonAndreas

Oxygen does permeate through rubber faster than nitrogen but with the atmosphere at 78% N2 and with tires specifically designed not to be porous membranes its meaningless.

The O3 floating around the outside of the tire does a lot more damage than the O2 inside the tire.

The keyword is supposedly. Water has a higher specific heat capacity than oxygen or nitrogen so it will absorb more heat without raising the temperature.

High-pressure, high-flow and inexpensive seems like a better reason why race teams would use it?

Leader

While there are those (supposedly knowledgeable folks) who swear nitrogen makes a real difference, with compressed air being 78% nitrogen already, any difference in a consumer car would be negligible at best. Most guys here would be well served to spend their time on other things than trying to find nitrogen to put into their tires.

ltc

There is one other potential benefit to using N2 in passenger car tires in the coming months...TPMS.

78% N2 air vs 100% N2 aside, since compressed/bottled N2 is dry, there is much less of a chance to cause humidity contamination of a TPMS sensor inside a tire/wheel.

As was mentioned, getting compressed air out of a standard air compressor in a relatively humid environment would introduce a substantial amount of water vapor into a tire's carcass, and under temperature/pressure, the PCB in a TPMS might become susceptible to humidity induced offset/errors (depending on how the circuit is designed and whether or not conformal coating has been applied to the PCB).

OCBen

Since when are tires made from Vamac (i.e. ethylene acrylic elastomers) ???

JasonAndreas

They're not but tires are made from Butyl rubber (its used to keep gas from escaping) and the chart (from Du Pont) shows the permeability of nitrogen and oxygen through Butyl rubber.

rmklaw

My winter tires were filled with Nitrogen. I noticed that the TPMS shows steady pressure regarding of temperature.

allegretto

As a Physical Chemist I doubt that this is the reason O2 leaches out faster. The real reason I suspect is that O2 is far more active than N2 and therefore dissolves itself into and then thru the rubber, and out the other side.

I furhter don't suspect that the conditions inside a tire are such that much O3 is formed.

But either way, the more inert the gas the better in an application such as this. Personally I fill my tires with Krypton. Keeps that ****ole Kent from borrowing the keys.

OCBen

Yes, Krypton (Kr, atomic number 36) is an inert gas that is rare indeed. Kryptonite, however, the element you would need to keep Kent at bay, is even rarer.