Dual valve stem wheels WTF

[Brentbohn]

Why do the new subaru sti have dual valve stems on the wheels... is this somthing we would benifit from ... whats the deal guys:2f2f:

[YoungGun]

2 chambers?

I know enkei makes a wheel like that, and I remember being told what it was for but I forgot.

[atom]

Nitrogen...........

You could also use the 2nd port to hook up a pressure gauge while filling. A little more convenient, I guess.

[SoguRacing]

Why do the new subaru sti have dual valve stems on the wheels... is this somthing we would benifit from ... whats the deal guys:2f2f:

maybe one is for the wheel pressure sensor??

[bblack_91240]

maybe one is for the wheel pressure sensor??

A buddy of mine has rims with two valve stem holes. One is for the stock tire pressure monitor so the tire pressure light isn't always on and the other is for a regular valve stem. I'm not sure why they needed a regular one though..

[Raskalking]

my guess goes along with previous statement of nitrogen. I don't know if thats the reason but if it is my understanding is that the density of nitrogen is slightly lower than air so nitrogen will float on top of air. So when filling with nitrogen through stem on top you can let out the sinking air since nitrogen is taking up space in the upper portion of the wheel. I guess kinda like bleeding the air so its mainly nitrogen in there. I don't know if thats the real reason they have em on that vehicle though

[VROOOM]

my guess goes along with previous statement of nitrogen. I don't know if thats the reason but if it is my understanding is that the density of nitrogen is slightly lower than air so nitrogen will float on top of air. So when filling with nitrogen through stem on top you can let out the sinking air since nitrogen is taking up space in the upper portion of the wheel. I guess kinda like bleeding the air so its mainly nitrogen in there. I don't know if thats the real reason they have em on that vehicle though


Correct


But there are some practical disadvantages. Filling pure Nitrogen into a tire isn't easy since you have to get all the air and moisture out. Most race teams with single valve stem wheels have to fill a wheel and then purge it three times to get it close to pure Nitrogen. That can get costly. Some wheel manufacturers like Enkie make a dual valve stem wheel like the NT03+M where one valve is use to fill with Nitrogen, while the other valve is for simultaneously purging the air. It might have been better if they placed the stems 180 degrees from each other for better purging instead of adjacently.

Enkie NT03+M Rims - Sport Compact Car Magazine (http://www.sportcompactcarweb.com/editors/sccp_0811_nitrogen_tire_inflation/enkie_nt03_m_rims.html)

[usajdm]

Dual stems, front/rear are for pressure reading systems.
An added benefit is for mounting the lower profile wheels on the "larger" sized rims(where the dual stems started becoming common place).

Remember, nitrogen filling has been around for quite some time, long before the dual stem set-up.

[s13dan]

GTR's have nitrogen filled tires if i rember reading correctly. Its lighter than plain ol air, and dosnt compress as easy..

woops ^^^ usajdm has gots the anwsers..

[mrmephistopheles]

Bee*R B5s have this feature as well, and again, it is for Nitrogen filling.

http://img205.imageshack.us/img205/6169/p1ia4.jpg (http://imageshack.us)

[usajdm]

So dumptrucks, tractor and big rigs since the 50's were running nitrogen in there tires huh?

[touge monster]

So dumptrucks, tractor and big rigs since the 50's were running nitrogen in there tires huh?

sometimes.

[Agamemnon]

GTR's have nitrogen filled tires if i rember reading correctly. Its lighter than plain ol air, and dosnt compress as easy..

woops ^^^ usajdm has gots the anwsers..

I always thought that nitrogen was prefered because nitrogen is a larger molecule than oxygen, thus it doesnt dissipate as fast as air, giving a more consistent pressure.

[usajdm]

^^^^^
Totally true, also helps to keep tire heat down and also helps preserve the life of a tire and rim by reducing moisture and oxidation.
As for the topic, the nitrogen fillers at the shop I work at and the airport I work at, require 1 valve stem and are never used at the same time as normal air.
When fillig with "normal air", it is put in after the nitrogen.
One machine we use actually dose it all, messuring out the percentages on its own and switching from nitrogen then finishing off with air.
Not Enkei or Work or any other "performance" wheel invented the dual valve design.
It was for mounting and monitoring oversized, overworked industrial tires.

[240sxnlr]

some of the heavy equipment tires have a second port for a water ballast...such as the Cat 980 front end loader...stabilizes the vehicle...it's a bear to change those tires...two stems on a passenger vehicle is interesting though...it would seem that the nitrogen explanation seems reasonable

[Om1kron]

Now this is an awesome thread! Tons of great info!

[Flicktitty]

Now this is an awesome thread! Tons of great info!
X2,

Anyone on here run Nitrogen in there tires? is it a noticable differance?
My girlfriends mom went to a toyota dealership to get her new tires mounted on her TC and thats what they filled them with, i was kind of suprised.

[usajdm]

I have it in my cars, the only noticable difference I can see/feel is the longterm consistency of pressure.
If it wasnt free, I wouldnt be doing it.

[!Zar!]

All it really does is leaks slower as well as it doesn't fluxuate in psi as much as a standard air filled tire does.

I had all my tires filled with nitrogen before I went to the track.

But I forgot to even care about trying to pay attention to how they felt.

It's a cool thing to have I guess?

I mean might as well. No real downsides.