Why use carbon dioxide in car tires?

Answer 1

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Whilst Bridgestone uses dried air by default, there are other gases available and teams will often try or make use of these in their pursuit for an advantage. In various series, not only in Formula One, nitrogen, carbon dioxide and other mixtures have been used. The most important consideration for whatever gas is used is stability or a predictable change in density relative to temperature change to enable the optimum tyre pressure to be both attained and maintained. A second factor can also be the reactivity of the gas with rubber, a point where oxygen scores badly. At high temperatures, the oxygen molecules in air can react with the rubber and hence reduce the tyre pressure. It is sometimes also believed that the mass of the gas is taken into account as being important, but the truth is that the differences are marginal compared to the other factors. Recently however, the FIA moved to limit the allowed gases to air, nitrogen and carbon dioxide. In order to allow the tyre to be filled completely with the specific gas, each rim has two valves, one to let air out, while the other is used to pump it up. * http://www.f1technical.net/articles/1?sid=080bc5a7b37ccc0ce4e700daa279e79d* http://e85.whipnet.net/alt.fuel/nitrogen.html