tire pressure

[Aussieflyer]

I agree that nitrogen in road going vehicles is a gimmick. Nitrogen is sold here as an 'upgrade' because it should result in longer periods between topping up the tyre pressure. The larger nitrogen molecule (when compared to the oxygen molecule) is slower at permeating the tyre carcas so therefore nitrogen stays in the tyre longer, 3 to 4 times longer. The motorist is then encouraged to check their tyres even less frequently!! This rather scientific paper explains in more detail: http://www.getnitrogen.org/pdf/graham.pdf