Postby Empress » September 18th, 2006, 10:51 am
What effect can Nitrogen have on tyres?
Under ideal conditions, Nitrogen will run cooler than normal compressed air, will exhibit slower leakage, have no oxidation, and be virtually non combustible.
In particular circumstances, pure Nitrogen is used as the inflation medium in earthmover, racing, and aviation tyres to where they are required to perform under conditions of high stress and in critical environments, generating higher than usual temperatures. Examples are:
* Where exceptionally high loads are carried by the vehicle,
* High-speed travel,
* Where high pressure must be maintained.
Also, in some instances, the tyre casing wears better, and to some extent, tyre tread wears more slowly, when Nitrogen is used in these extreme circumstances.
How can Nitrigen affect on-road tyres?
Despite the advantages in specialised tyres subject to extreme conditions, the benefits of Nitrogen inflation for tyres used primarily on ordinary roads in standard driving conditions are not at all clear.
The main arguments put forward for its use of pure Nitrogen in tyres under normal conditions are:
a) Alleged Improved Tread Wear
Unfortunately, little controlled test data exists to support or refute this claim.
Improved tread wear comes from proper tyre maintenance, for example from:
* Checking your tyre inflation pressure at least once a month, and preferably fortnightly
* Regular rotation and
* Correct wheel alignment.
Take care of these, and your tyres will ride more safely and wear better, irrespective of the choice of inflation medium.
b) Casing Durability
When the tyre heats up, moisture in the tyre vaporises and expands. In some circumstances, moisture in the compressed air in a tyre can gradually migrates through the inner lining of a tubeless tyre and into the steel-cord body plies, resulting in rust, which ultimately causes casing degradation.
This applies to truck and bus, and some light truck tyres. Passenger and most light truck tyres are not affected, as they are composed instead of textile body ply material (eg polyester, nylon, rayon, etc).
One of the main claims made by Nitrogen proponents is that compressed Nitrogen contains less moisture than compressed air, thereby reducing the incidence of this moisture migration effect.
The primary aim should be to avoid moisture migration irrespective of the mix of gas used in tyre inflation. Moisture can be introduced into the tyre as a result of poor workshop practices and incorrect or inadequate tyre fitment procedures.
To this end, we encourage proper selection of compressor equipment, air-line routing, the use of air dryers, and other sound workshop and equipment maintenance practices in order to minimise moisture introduction.
This applies both to initial tyre inflation and top-up air.
Poor tyre fitment and workshop standards can also contribute to wheel and rim corrosion. If proper practices and equipment are utilised, moisture migration is minimised. It does not matter so much whether Nitrogen or compressed air is the inflation medium.
If you fill your tyres with Nitrogen, to retain any benefit, you will need to top up with Nitrogen as well. Topping up with Compressed air will negate any benefit.
When you first fill up your tyres, they already have air in them, so they really should be filled then evacuated, then filled again to remove the residual atmospheric air.
c) Susceptibility to Tyre Fires
Ever since the introduction of tubeless radial-ply tyres, the risks of tyre fires and/or self-ignition of tyres due to excessive heat have been rendered virtually nonexistent.
With tubeless radial-ply tyres, there is no 'tube and flap' which could cause friction and, therefore, heat to be generated.
It takes far higher temperatures to ignite steel radial truck and bus tyres, as compared with fabric-reinforced bias-ply tyres.
If properly maintained and used within legal tolerances, air-inflated passenger and light truck radial tyres will rarely, if ever, generate sufficient heat to self-ignite and burn, whether filled with Nitrogen or with ordinary compressed air.
Those motorists who choose to keep their tyres inflated with Nitrogen must bear in mind that Nitrogen inflation is NOT a 'set and forget' option. Regardless of the gas inflated into your tyres, to preserve their safety characteristics and longevity, you must check tyre pressure tyre and condition regularly.
