It's 78% of what you breath

Pick your non-poison. Air, like in the States (at least in some places) is free, but Nitrogen will cost you up to R$2 extra. Supposedly it will make your tires last longer by not allowing them to heat up so much while driving all over this hot hot city in the summer - an important detail where potholes the size of the car itself are not so "news worthy" as they should be. Sounds like a good deal, right? But how much longer will your tires last? No one seems to know. Another important point - no mixing allowed: once you choose N2 as your preferred gas, you have to stick with it. If you happen to be low and go to a station that doesn't have nitrogen available, you'll have to completely drain your tires and refill them with air. The infrequency N2 pumps in the city is what prevents us from putting it to the test.