In part 4, we learned how researchers test steel belt rubber oxidation in a laboratory, which is pertinent to preventing the types of accidents that led to the 2000-2001 tire recall. Here, we’ll discuss what can be done by typical drivers to protect your tires from oxidation.
Three approaches are immediately apparent. One approach is to mix anti-oxidants with the rubber. Although tire manufacturers use this approach and it is an active area of research, anti-oxidant technology is based on proprietary knowledge and is not something that can be applied by consumers.
Another approach is to change the composition of the rubbers comprising the tire inner liner. For example, replacing all of the natural rubber with halobutyl derivatives—in comparison to a 6:4 ratio—decreases gas permeation by a factor of 2 or more, and improves the time to failure in a standard load test by more than 60%.
This improvement was the industrial standard in 2008. More advanced developments are in progress. Nevertheless, this is not something that can be applied by consumers.
A third approach is something that’s available to everyone: nitrogen inertion. Both computer models and experimental data predict that the rate of oxidation lessens when the oxygen concentration in the tire decreases from approximately 2.5 atmospheres of pressure to approximately 0.2 atmospheres, i.e. the concentration of oxygen in everyday air. Beyond that, there doesn’t seem to be much improvement in oxidation resistance.
This suggests that the anti-oxidation benefits of nitrogen inertion do not necessitate a complete purge of the air in your tires. This renders nitrogen inertion more practical and less expensive for the average consumer.
Nevertheless, other considerations such as the water (liquid and vapor) in your tires may still cause problems without a complete purge. Diurnal temperature fluctuations and the increase in temperature occurring in your tires while driving have more of an impact (e.g. on fuel economy) when water is present, as it always is in standard compressed air.
- M. Baldwin and D. R. Bauer. “Rubber oxidation and tire aging – A review.” Rubber Chem. Technol., 2008, 81(2), 338–358. http://dx.doi.org/10.5254/1.3548213