Benefits of Nitrogen in Motorsport

Over the years I often get asked about Nitrogen in Motorsport Tyres.

The biggest benefit in using Nitrogen is when your tyres and wheels are working at very high temperatures (Circuit Racing and Tarmac Rally). The main reason for this, is controlled pressure expansion at the top end of tyre operating temperature. When using only air, you risk a vast range of inconsistent impurities in your tyre from additional moisture, vapours and fumes from compressors motors etc causing radical and continuous spikes in hot pressure.

By volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere.

Let’s consider your brakes are at 600*+ and the transferred heat into your wheel is 100+ degrees and your tread temp are around 80* then the moisture in your tyre will flash/expand. It’s like pouring boiling water into a plastic container and trying to put a lid on it, it just keeps popping off. So, by raising the Nitrogen purity to around 97 to 98% and eliminating impurities, this will bring consistency to your racing and the ability to set up your starting pressure at a point where your hot pressure is stable at your desired hot pressure.

Here is an example of why this competitor needs Nitrogen:

“Matt has a BMW Tarmac Rally Car and on the first morning of a three day rally he sets his tyre pressures to 24 front and 22 rear as he wants to run at around 30psi and; 28psi hot. He checks his pressures after the first stage and they are all-ready up to pressure (Matt’s a Maniac). After stage 2 he checks them again as he is not so happy to find them now at 34psi and; 32psi so he reduces them while they are hot back to what he wants. Over the day he has to keep adjusting as the grip level over his desired pressures is taking away the performance. The next morning Matt checks his tyre pressures and he finds 18psi LHF and 17psi RHF and Rears at 16psi. So, the service crew start up the old compressor and pump them back up injecting more moisture back into the tyre.”

In this application if Matt had Nitrogen his next morning cold pressures would be set to go as there would have been no moisture flashing through out the day and his tyre pressures would have been much more stable improving his driving experience.

Things to keep in mind.

Ensure your tyres, when mounted, are beaded using Dry Air or Nitrogen. There is no point purging a tyre with Nitrogen if it has residual moisture from its first inflation.
Your cold pressure may still be the same as oxygen but it will find a limit of expansion at hot operating temperature.
Nitrogen still expands but at a linear rate.
At a circuit racing track when using Nitrogen while testing, you will be able to find exact tyre pressure stagger for the given track.
Just filling your tyres once with Nitrogen will not give you any benefit. You need to purge the tyre correctly to raise the purity.
SA Motorsport Tyres has its own Nitrogen generator and dry air system.
You can buy your own rechargeable Nitrogen Bottles and inflators to take with you as minor pressure changes will be required from time to time.

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