Nitrogen

[bulldoezr]

I have gained access to a nitrogen tank and was thinking of trying it in my tires. Does anyone have any idea what to do with pressures? With regular air I was running around 28psi cold, maxing at around 37 or 38. I know nitrogen doesn't gain the pressure as much as compressed atmosphere, but should I start my pressures higher? I mostly like the idea of not having to plug a compressor in at the track or having to go keep filling an air tank, not to mention being able to run other air tools off the tank. Any input would be great.

[rsportvolvo]

Set temps cold and then adjust hot. The pressure won't "grow" as much as there is less moisture in nitrogen vs. compressed air. This is of course dependant on ambient conditions where the air was compressed. When the tires cool take a pressure reading. That's roughly your cold & hot pressures. The you can fine tune from there. If you want, you can record pressure & temp and get a correlation there.

[bulldoezr]

So I should start at my normal pressures? The car handles like crap the first few laps normally and gets really good toward the end of a run. I was thinking I should start out in the low 30's on pressure, but I simply have no idea how much the pressures will increase.

[rsportvolvo]

So I should start at my normal pressures? The car handles like crap the first few laps normally and gets really good toward the end of a run. I was thinking I should start out in the low 30's on pressure, but I simply have no idea how much the pressures will increase.

If the tires are working well @ 37-38 psi then I would start @ 3-5 psi lower for starters using nitrogen and then bleed off pressure as required to get back to 37-38 psi. It's much easier to pit and bleed off pressure vs. adding more nitrogen. You'll have to do some testing as this depends on ambient conditions, grip, track surface, car suspension, etc.

[JoshS]

My tires gain 4-5 psi using nitrogen.

[Harvey]

If you don't purge the tires first to get rid of the moisture you will not see a lot of benifit from using nitrogen.

Les Chaney

[bulldoezr]

I have been told to pump the tires to 50 or so, let the gas out most of the way and refill to pressure. Should this be done more than once?

[joeg]

Les is correct. If you just inflate an empty or almost empty tire with N2, it still has regular air in it. When the tire was mounted, air was used, so that would need purging and probably the only way is with two valve stems on the wheel and a vacuum system attached to one.

Accordingly, in the absence of such a system, don't get your hopes up that you are running pure Nitrogen.

[jimbbski]

One other thing I've heard is that the nitrogen molecule is larger then an oxgen one so you should lose less pressure through tiny leaks that may exist in the tire or rim.

[Greg Amy]

The value of nitrogen in tires is easy: dryness. Regular air has moisture, nitrogen is dry; ergo, the pressure change with nitrogen is more predictable.

Find a way to "dry" regular air and you'll get the same performance from it. Then again, tanks of nitrogen are pretty damn cheap and unless you're tire busting every weekend should last at least a season.

GA

[joeg]

For super deep pockets (F-1):


After extensive tyre testing the best blend of HFCs was found to be 52 per cent Tetrafluoroethane, 44 per cent Pentafluoroethane and four per cent Trifluoroethane. This mixture, known as HFC R404 A, was found to be most effective in a racing tyre when it was inflated with a blend of 50 per cent HFC R404 A and 50 per cent CO2. The use of refrigerant gas to cool the tires and radiate heat away from the carcass through the wheel is but one of many Ferrari secrets McLaren was privy to.

[bulldoezr]

Thanks for the input everyone. Going to run it this weekend and see what it does. I think the ease of not running that loud clanky compressor will be a nice change.

[Jimberry67]

Nitrogen on its own is negligibly affected by everyday heat (I deal with it all the time). Start out at recommended tire pressure, run a few hot laps pull into pit lane and have a assistant hit your tires with a pyrometer on the inner / middle / outer tread on each tire and add or subtract pressure until you get as even of a temp as you can all the way across each tire patch. Remember, driven wheels are going to most likely have a different pressure setting from driving wheels and different caster / camber will affect as well. Another thing to remember different tracks and conditions will affect HOW you want your tread contact patch to be set up. but once you find that sweet spot you got it wired

[ShelbyRacer]

The value of nitrogen in tires is easy: dryness. Regular air has moisture, nitrogen is dry; ergo, the pressure change with nitrogen is more predictable.

Find a way to "dry" regular air and you'll get the same performance from it. Then again, tanks of nitrogen are pretty damn cheap and unless you're tire busting every weekend should last at least a season.

GA

+1 (actually, plus 50 if I could)

Many tire shops that supply nitrogen in large volumes (they have it readily available via a "generator") may have moisture issues, negating most of the benefit of Nitrogen. Please be wary.