anyone ever hear of filling your tires with hydrogen or helium or something? i know this may seem stupid but jw. thanks

 

most common practice is nitrogen. Helium will expand to much as it heats and hydrogen is terribly explosive(ever hear of the Hindenberg(sp?)). Nitrogen is used by pro teams because as nitrogen heat up in the tire it does not expand as much as "air"(60% or so nitrogen any way). Pro teams also have notrogen at hand as this is what powers all there air tools at the track as compressors are not used for safety reasons. I have tried nitrogen and I have found I can't tell the difference, check tire temps and pressures. One of the things that affects how much a tire expands as it heats is the water content in the tire. Yes, water will be suspended in air as you inject into the tire and as the tire and air heat the water also heats and expands. Lots of things to worry about, but easiest thing to do is monitor the tire pressures and temps and adjust the pressures during the event.

 

hydrogen is relatively safe hindenburg was caused by other issues that i forgot ever hear of hydrogen fuel cell vehicles? but who cares thanks =D

 

Helium=safe, Hydrogen=BANG!!! One of the issues with hydrogen fuel cells is protecting the little bomb from getting smacked in a collision. Its just a different problem from gasoline, gas has enough power in a gallon to send you, three friends and a Buick about 25 miles.
Besides that, tims covered the use of nitrogen very thoroughly for you. Its what we use when its available.

 

If you can get a source of DRY air, then that'll get you at least 90% of any benefits that Nitrogen will give you, as normal wet air expands as much as it does partially due to the water content.

 

Hydrogen is relatively safe unless it gets near a spark or something hot - I wonder if my car has any hot spots. Hmmm....

 

This is rich.

Hydrogen is not a monopropellant. Meaning, it needs to combine with something, like say OXYGEN, to get a nice bang.

Hydrogen tanks, or a theoretical hydrogen-filled tire, wouldn't be a fire or explosion risk unless you first mixed oxygen wih the hydrogen. And I say theoretical because hydrogen is really, really hard to store, it can leak through *anything*.

Gasoline isn't a monopropellant either, which is why there's no problem with having sparky worn out fuel pumps running unsealed directly inside fuel tanks. No oxygen in there, either! (Fuel vapors generally keep the tank pressurized, so there's no way for air to get in except by force)

 

yeah because i just worked with the california fuel partnership last year and i remember convering all this..i just forgot. well about combusiveness of h2 that is..

 

I have heard of nitrogen and Argon becuase they are more stable and expand less due to heat.

 

^^u must be an Initial D fan...

 

 

The major problem with using either hydrogen or helium is that a) they're expensive and b) they're both very small atoms/molecules and will diffuse through the tire wall and disappear. This is part of the reason hydrogen tanks need such thick walls (plus pressure concerns). Since air is 78% nitrogen, it is cheap to obtain. As black91n/a noted, most of the advantage to nitrogen inflation is because it is dry. Dry air would be about 78% as good. However, compressed N2 is the easiest, cheapest source of dry gas for tire inflation.

On a street driven car or even a serious autocross car, you'll never be able to tell the difference. For most people, its just the latest fad. I've seen one suggestion on Miata.net (where wheel weight is a religion) that filling with helium would reduce unsprung weight!

 

Technicalities, yes peejay is correct about both gas and hyd. needing something else to go boom but the fact the atmosphere down here is about 20% full of the stuff either gas needs I'll continue to use nitrogen in my tires.
And I'm sure we've all been told you can put a cigarette out in gasoline, I'm just not going to show up in the Darwin awards trying. Oh yea, I already have a kid so I'm disqualified from that award...

 

There's a big difference between fuel all by its lonesome and fuel mixed with air. That's why it's perfectly fine to have a brush-type electric motor (which DO make sparks, especially when they are old and decrepit) in a fuel tank surrounded by 100% fuel vapor.

Now if you're worried that a leaky tire might turn your car into a nice FAE bomb then you might have a point. (FAE's are nifty antipersonnel weapons, they are just fuel tanks that atomize the combustible into the air as it travels. Then when it's empty it ignites the mess. WHUMP!) But the tire itself isn't going to pose a problem internally.

And yes I've thrown lit cigarettes into puddles of gasoline. They just go out. Lit *matches*, on the other hand... also go out half the time.

 

July 1996, TWA Flight 800, 'empty'(about 300lbs of fuel) center tank explosion. That's probably the most famous one I can think of but as a pilot I can show you a list filled with transport and military aircraft that have gone down because of this and that's with jet fuel.

Half the time with matches huh? How long till your eyebrows grew back after that experiment?