Show determining LIFE OF TIRE ordinarily the more air the longer it will last safe to start with 20 pounds the life 0 of f a tire Is the air it if con on enins the more air ordinarily the longer the hie life of course there tire exceptions lint but it Is a safe rule to start with 20 pounds of air pressure to tho the cross section inch mid and if more la is needed to mill add to it thus thu a three antl n hair inch tire will require 70 pounds and a four inch tire 80 pounds noad head load and speed lire determining factors fiK tors in the pressure required |