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Old 05-14-09, 08:42 AM
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deraltekluge
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Originally Posted by cyccommute
Sorry but it's all driven by pressure. Mountain bike tires are run at low pressure which means less energy driving the diffusion of the molecules. Higher pressure tires means more energy driving the diffusion.
But smaller tires have less to leak, so the same amount of loss would result in greater change in pressure. All other things being equal, the loss rate would be proportional to the tire section size, but the volume is proportional to the square of the section size...a tire half the size would lose air half as fast, but has only a quarter of the air to start with, so pressure would drop twice as fast as with the bigger tire. Of course, as I said, "All other things being equal." But they never are...loss is also proportional to pressure, and if the bigger tire uses half the pressure, it'll lose air about half as fast.
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