SL55/63/65/R230 AMG: Nitrogen filled tires
Ok oK.. a more scientific answer...
"Nitrogen is a very unreactive gas. If you fill a tyre with dry nitrogen gas, it is possible to predict how much it will expand as the tyre heats up from friction with the road. Air on the other hand is an unpredictable beast. While its composition is always the same, consisting of 76% nitrogen and about 20% oxygen, the amount of water in it can change from minute to minute and this water makes the expansion of air very unpredictable.
The height of a racing tyre is critical to a couple of millimetres. If the pressure in a tyre is too high the car will be difficult to steer and if it is too low the car may scrape the track, so race engineers need to know exactly how much the gas in a tyre will expand during a race. In the extreme situation of a crash the fact that nitrogen expands less than oxygen when heated means there is less chance of the tyre exploding during a fire. Tyres can explode with the force of a dynamite detonation, which increases the risk already faced by rescue crews.
This is the high performance end of the spectrum, but nitrogen is also used in the tyres of more every day vehicles. Long distance lorries often use it as water in air oxidises the rubber in tyres causing them to corrode. Over longer periods gas also diffuses out of tiny pores in rubber tyres. As a nitrogen molecule is larger than an oxygen molecule it leaks out of tyres three times slower than air, which maintains tyre pressure and therefore tread wear. All in all, using nitrogen in tyres can more than double their lifespan, although for the flimsy racing tyre which needs changing several times in a race nothings going to make that much difference."
http://www.bbc.co.uk/science/science...ingtyres.shtml
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But you know what. Even after all of that. I will still be afraid to try nitrogin on my tiers.
Any gas tank can be exploded when too much heated .
Pressure in tyre with air can not be stable.
If you have tyre pressure monitor option at your SL55,
try it with different ambient temperatures.
You will find out the pressure varies and sometimes
there is a difference among 4 tyres which were filled
with same air pressure.
I think this variance came from humidity which any air compressor has it ( some compressors emit oil with humidity).
As you know, humidity can change the air pressure in tyre
very easily according to the tyre temperature affected by
running as well as ambient temperature.
The humidity you can not remove 100% from the pressurized air.
The only way to remove it is to fill the tire with a 100 % gas .
Q: Why do NASCAR Winston Cup Series teams put Nitrogen in the tires? What purpose does that serve?
A: We use nitrogen because it's a cleaner air; there's no moisture in it. Moisture builds heat, and when you use compressed air, there's a lot of water in the airlines and air systems, and when that water gets into the tire, it will expand the tire and puts heat into it, and will eventually cause a tire problem.
For those of you who remember chemistry, Nitrogen is a noble gas, which means it is very inert. Get a small tank of nitrogen, fill a beaker with nitrogen, and cap it with a glass dish or something. A match put into there will extinguish almost immediately because oxygen is needed for combustion, and nitrogen doesn't burn.
-Jordan







