Filling your tyres with Nitrogen

[cainchapman 0]

OK, this should maybe be posted in the race forum as I am specifically looking for answers as it relates to Motorsport. It is for another National Class of racing, so I'll post it here. I have been doing research, so I'm keen to see what the popular reasoning is out there, before I respond.

Filling your race tyres with Nitrogen.

Why do you do it?

[conrod 1]

Nitrogen does not contain the moisture that air does, so when heated (as happens in racing)nitrogen does not tend to increase in pressure as much as air does, in other words, you get a greater pressure increase on hot tyres filled with air, than you do with nitrogen. BTW, to do it properly, you really need to evacuate ALL of the air from the tyre, before filling it with nitrogen, which requires a special vacuum pump. Just deflating and filling with nitrogen still leaves some air in the tyre.

Edited November 13, 2006 by conrod

[Guest Spargo]

1. Slower rate of pressure loss.

2. Cooler running temperatures.

3. Reduced pressure build-up.

4. Reduced amount of oxidisation of wheels.

[cainchapman 0]

OK, Conrod & Sam (who googled his answer).

If I banned you from using Pure Nitrogen to fill your tyres (can't ban it, as it comprises 78% of Air), what would you do?

[conrod 1]

OK, Conrod & Sam (who googled his answer).

If I banned you from using Pure Nitrogen to fill your tyres (can't ban it, as it comprises 78% of Air), what would you do?

Assuming it is the world-championship-whatever that we were competing for, I would probably fit those little bleed off valves that the speedway guys use, until you banned those too!

[nz320i 0]

conrod can i see some pics of your race car? in rides or something ?? ive never seen an update of how it came along..

[conrod 1]

conrod can i see some pics of your race car? in rides or something ?? ive never seen an update of how it came along..

It pretty much looked as it did in the last pics I posted, before I sold it, and bought the M3. You do realise it is not the same car?

[Guest Spargo]

The correct answer is still the correct answer, work smarter not harder

Besides, i've got an exam tomorrow that I should really be studying for.

The only time i've used nitrogen for tyres is in super mini racing.

Argon would be a good choice if you could get hold of it.

[cainchapman 0]

Conrad's answer is more correct Sam. The main reason is the water component. Your first point about Nitrogen be less permeable is correct, however, in the real world. No-one cares. The tyre pressures are checked and adjusted between races. Points 2 and 4 are correct, it is not due to the characterstics of Nitrogen, but the water content (and Oxygen in point 4).

Point 3 is completely false. Nitrogen has a lower thermal co-efficient than Oxygen, so Air heats slower than pure Nitrogen.

If you trot down to BOC and buy a cylinder of Compressed air, it contains about 10 parts per million (ppm) of water vapour. This is not significantly different to purchasing a cylinder of Anhydrous Nitrogen. So both will have similar thermodynamic performance. But it very different than going down to the Petrol Station or using the sh*t air compressors you can buy from any Auto-supply store.

The breathing air standard deems water vapour must be less than 150ppm to give you an idea of how good the BOC cylindered air is compared to atmospheric.

Anyway, my point was, banning a class from using Nitrogen will not penalise the larger teams, only the smaller ones. We always have cylindered air or Nitrogen at a race, so tyre pressures are fairly consistent.

[Guest Spargo]

How do they test for nitrogen during scrutineering? As you say air is 80% nitrogen anyway, so how does that 20% of other gases affect performance that much?

Is it purely down to hydrogen and oxygen combining - thus the BOC gas "air" with 10ppm of vapor being preferable due to their being less chance of more water forming than is already there?

[Jimocles 0]

we see this arguement alot in the NZV8s some guys use it some don't, and laptimes don't really seem to vary enough

to make a strong case for its use. of course there are so many variables in every lap it is a hard thing to ascertain how much of an advantage it really is, on a stinking hot day, I suspect the gains would be more noticeable.

but with set up differences, different tyre pressures, and sheer driving ability, Nitrogen as an advantage is negligible the dryness factor is the most pressing case for its use

no doubt someone with alot more scientific knowledge than me can tear my statement to shreds,

these are more my observations based on experience from 5 years working on tyres at top level events

[cainchapman 0]

Testing for Nitrogen is easy. You test for the depletion of Oxygen. I am happy to assist in the supply of this for the administrators of the class. However, they are better to advise people of how to fill their tyres to gain consistancy across the class, rather than spend money policing a very small issue.

Hydrogen makes up 0.5ppm of the composition of Air, so has no effect at all.

There are real benefits to using Nitrogen in Aircraft (much higher pressures and generally around really hot stuff) so when a tyre blows, you don't want 7-20 bar of Oxygen in large volumes around. And in the trucking industry as the tyres degrade slower and pressure leakage is reduced.

However, race tyres don't have these issues.

Brochure_Pac_7000.pdf