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Motorsport Wheel Alignment: Nitrogen vs Air

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Nitrogen vs Air


00:00 - While it's commonplace to fill the tyres in our road cars with compressed air, that actually isn't the best option for a competition car and instead we're better to use nitrogen.
00:10 There are a few reasons behind this choice but predominantly it comes down to maintaining a more stable tyre pressure as the temperature of the tyre changes.
00:18 Let's consider why that's the case.
00:21 The air we breathe, which also constitutes what we put into our tyres as compressed air, is predominantly nitrogen, about 78% to be precise.
00:30 21% is oxygen and then the remainder is made up from other gases as well as water vapour.
00:36 One of the issues we see with tyre pressure is that it will tend to drop over time as compressed air in the tyre can escape through the rubber.
00:44 In general, for our purposes this is not a huge concern since it happens very slowly and certainly not fast enough to have a measurable effect over the course of a race.
00:55 Irrespective of this however, we do find that nitrogen doesn't migrate through the tyre at the same rate as compressed air and therefore our tyre pressures remain more constant and stable over a long period of time.
01:08 The more important aspect though is that the water vapour that inevitably makes up a component of the compressed air, will result in the tyre pressure changing more for a given temperature change, compared to using dry nitrogen.
01:21 While we're still going to see the pressure increase from cold when running nitrogen, it's going to be more stable and consistent than what we'd see with compressed air.
01:31 The water vapour in compressed air also has another downside in that it can promoto corrosion of steel or aluminium rims.
01:38 This is more of a concern in very humid regions where there will be more water vapour present in the air.
01:44 However it's still a consideration as nobody wants their expensive wheels damaged needlessly.
01:50 So now that you're sold on nitrogen to fill your tyres, the next obvious question is how do you do it? And unfortunately this is a little tricky since service stations and garages which are the most common places to pressure tyres in your road car, normally won't offer nitrogen.
02:06 Some tyre shops are now offering a nitrogen filling service since the more consistent tyre pressure nitrogen offers is also an advantage to tyre life and fuel economy in a road car.
02:18 This means that there's a good chance a local tyre shop could offer a nitrogen fill for you.
02:24 This is helpful to a point since most enthusiasts who are attending track days will probably fill their tyres slightly above their target pressure before heading to the track, meaning that they only need to drop pressure out of the tyres during the day.
02:38 This won't of course help if you need to add pressure during the day.
02:41 For this task, most serious racers will take a high pressure bottle of nitrogen to the track with a regulator and a hose so that they can pressure their tyres as required.
02:50 You'll be able to rent these nitrogen bottle from your local industrial gas supplier, however there is the cost to consider for both the gas as well as the bottle rental.
03:00 Your personal choice will come down to how much racing you intend to do and what your budget is.
03:06 However if you're only thinking about attending a few track days a year, then don't think for a second that nitrogen is an absolute essential and you'll still be able to have fun and go fast with regular compressed air.
03:18 One last consideration when using nitrogen to fill your tyres is that there is a process to go through to initially inflate the tyres with nitrogen.
03:26 This is because naturally, some ambient air will end up trapped inside the tyre when it's first mounted on the rim and this needs to be evacuated and displaced with nitrogen, otherwise we won't get its true benefit.
03:38 This means that if you rent a bottle of nitrogen, just letting the air out of the tyres and refilling them, isn't enough.