Its not an exact science, but in general, more air, less rolling resistance, but less traction going around corners. Less air, more grip around corners.
I keep my front kinda soft, 80-90 and the rear pretty high, 110-120. This way, the front, which tends to slide first, has good grip and the rear, which carries most of the weight, has less rolling resistance.
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Il faut de l'audace, encore de l'audace, toujours de l'audace
1980 3Rensho-- 1975 Raleigh Sprite 3spd
1990s Raleigh M20 MTB--2007 Windsor Hour (track)
1988 Ducati 750 F1