Since oxygen permeates much faster, the simple way to get 92% Nitrogen is to fill to 50 psi and let the oxygen permeate out:
http://www.nhtsa.gov/DOT/NHTSA/NRD/M...094.pdf
Quote:
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if a normally maintained in-service tire is not punc*tured or deflated, the faster diffusion/consumption of oxygen relative to the nitrogen content ofthe inflation gas results in an increase in the percentage of nitrogen gas from the original 78 per*cent to as high as the 91 percent observed, thus lowering the effective rate of inflation pressureloss.
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They didn't use such high inflation pressures, but it's an interesting idea... considering many hypermilers use significantly higher than the 29 psi used in the field aging test.
Want 95% nitro? Keep filling with 60 psi, and eventually, you'll get there.
