thomas1978

i need to try this one ) lol

Capt William

The only difference I can think of would be oxidation on the inside of the tire. Air is essentially 80% nitrogen and 20% oxygen with traces of assorted other gases. Both oxygen and nitrogen behave as ideal gasses at the temperatures and pressures inside a tire so things like rolling resistance and handling would be uneffected. I can't imagine much of difference in seepage since both oxygen and nitrogen are so close in molecular size and again because air is primarally nitrogen anyway.

If someone has some real data on this I would be very curious to see it. Perhaps filling your tires with completely dry gas 9nitrogen or otherwise) might make a difference but even then the rubber in tires probably has in it and absorbs large quantities of water anyway. I can't even see any obvious advantage to a gas with exceptionally high or low thermal conductivity because there is no where for the heat to be transported inside a tire. This one is a real head scratcher for me.

Capt William

there is no difference in the expansion characteristics of nitrogen vs. oxygen nitrogen (air) since they are both ideal gasses at the temps and pressures in tires.

6sidua

will yeild a wealth of info....most is not great but clearly this is big business as major companies are making the equipment and shop costs to upgrade run into the 1000s of $.

it looks like there is some good data reports on extending tire life 20-50% on big trucks, heavy equipment and high speed transports in europe....

so industrial, military, aerospace, cycling AND race cars seem to be on the nitro wagon....pretty much all users except personal automotive....so it had to happen.

add to that jay leno using this system and well!!
sign me up!!

Capt William

Moisture may cause some greater variation in hot vs. cold tire pressure and since the nitrogen is dry (supossedly anyway) it should reduce this. The issues of reactivity of oxygen do not realistically apply to car tires or wheels. I can not recall ever having a problem with corosion inside of a wheel. Likewise I have never heard of a passenger car tire (whether on a Kia or Ferrari) ever burning internally from heat. I read some claims of slower loss of pressure when using nitrogen but I am suspicious of this and in any case I have not noticed this to be an issue on tires (wheels, valves etc.) in good condition.

It seems to boil down to (no pun intended) that the only possibly significant advantage might be due to the fill being lower in moisture and you may not even get that advantage when filling with nitrogen. It turns out that most places selling nitrogen fills for tires are using nitrogen generators (more properly call separators because they separate oxygen and nitrogen from air with a molecular sieve) so, unless they are also drying the nitrogen they may not have any advantage.

Capt William

And for companies to sell tire stores molecular sieve nitrogen separators. I think a serious dryer for compressed air would work just as well for our purposes.

Aircraft tires use nitrogen for a bunch of reasons that don't apply to car tires. Aircraft tires run much higher pressures than car tires, sometime hundreds of psi. High performance aircraft use braking systems that are encased inside the wheel and in addition these brakes get much hotter than car brakes. When I was in the USAF I had heard of mechanincs being killed when tires exploded because the brakes had gotten so hot (and therefor the air inside the tire) that the pressure increased enough to burst the tire). It is much more difficult to get air for aircraft tires at airports so they often go for long periods without being checked of reinflated. Likewise, just like everything else on aircraft, wheels are insanely expensive and aircraft tend to have much longer lifespans than cars so corrosion on wheels might actually be a serious concern.

We tend to get seduced by the notion that if airplanes or NASA or the military use something that it must be more "heavy duty" or some such nonsense. I am not saying that there is nothing to the nitrogen fill but as I said before you could probably get all the significant benefit with dry air. But it has got me thinking that I should do some experiments...

April

We live in a somewhat humid area, and so regular air in nice expensive Hoosiers (with a max fill of 35psi cold on regular air) sees a lot of expansion under racing conditions. Makes for inconsistant times and uneven wear. Nitrogen fill keeps pressure change at virtually nil.

technokid

Was talking to Pirelli booth (don't know what team) at Laguna Seca and they said nitrogen was costing them $8000 a year for tires. Said dry air system was cheaper, and is about 15% drier than nitrogen.

TXurS6

Mainly if you track your car. Tire temperatures go out of the normal bounds of daily driving and the moisture in the air can make the tire pressure fluctuate more than normal.