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Is there a low cost way to fill tires with nitrogen for HPDE events?

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racer47

Still winning after 30+ years
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Its not worth the effort imho. If you have an air compressor at home, drain it once in a while and you'll be good.
 

Fabman

Dances with Racecars
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Try a welding supply shop: Praxiar, Airgas, etc. You should be able to buy a small bottle and regulator and have it refilled whenever you need to.
This is exactly what I do. I have a big bottle that I fill the sticker tires with and a small bottle that I bring to the track for pressure adjustments.
There is a lot of debate about whether or not nitrogen is necessary for a track car.
I'd say in most situations it probably isn't. But I've \been racing on slicks for decades and have always done it, so I continue to do so. My pressures grow far less, far more predictably, so...why not? First few laps while other drivers are getting their tires up to temp and pressure I'm already there...so again, why not?
 
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Fabman

Dances with Racecars
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I'll tell you a little story, and how I know how much nitrogen and air differ in expansion rate, I ran late model stock cars for decades. We use a fully locked rear end...a "Spool" so both rear tires are solidly locked together. One major tuning tool we had was to adjust the rear stagger (RR tire is bigger than the LR tire) to help it around the corner. Problem is, when you buy tires you don't always get the exact stagger you wanted no matter how much you plead with the tire guy. So when I fell short on stagger I would put Nitrogen in my LR and Compressor air in the RR and as the tires warmed up on track the stagger would increase. I could start with an under-steering pig and end up with a neutral or over steering car within a 25 lap race on as small as a 1/4 mile track. I've seen the Hoosier full slicks that we ran grow as much as 1 1/2 ". That's a bunch. Granted they were bias plys, so they stretch more easily than radials, but the pressure grows regardless of the tire type and whether or not its actually getting bigger. Winston cup cars fine tune spring rate with pressure, a tire is also a spring so small changes in PSI have a noticeable effect on handling beyond deformation rate. You're adjusting the spring rate as well. Again, this is probably not critical for most track day situations but know that its real and totally appropriate in the right situations.
 
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IMHO, it’s not worth it. Yes we haul ass, heat up tires, but we are not doing 30,000 plus feet above sea level flights and going ove r600 mph. Now if you're a LSR racer then look into it.
 
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Take your home air compressor, install a couple of inline driers and call it a day. There's more to running nitrogen than just filling the tire with it, some of that info is proprietary, so I'm not at liberty to discuss it, but it's all on the net if you look hard enough. Nitrogen is absolutely the way to go, BUT, the key is to keep moisture out of the tire, if you do that, you are about 60% of your way to consistency. The example Fabman gave is a perfect one, (even though they run bias tires) the growth rate between nitrogen, regular air and dehumidified air, are all different.
These are different graphs developed over the years, the top is pretty much a random graph based on what I knew 10 years ago, and it was Nitrogen based, I don't remember which track it was but there are only 7 "tires" shown because tire #8 was identical to one of the others. These were divided into RF, RR, LR and LF -over a bunch of sessions
Graph2 is when I started figuring it out, and things became much more consistent, this graph prolly contains several hundred samples, not quite perfect, but closer and predictable
Graph 3 is a generic showing the difference between air and nitrogen, dehumidified air should be someplace in the middle
Most guys, if they are really leaning on it will average tire temp around 200 or 210, sometimes higher if they are really on the button.

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