every 2-3 months once~
jus refill it will do n no need to deflate n re-pump it~
everybody always neva notice d sign of losing air pressure but every month they losing sum air inside n they neva notice it tills it goes very lose n gice bad fc only pump n it's bad for d tires cuz everytime wen there's not enuf air,tires will intend to wear out on both shoulder faster than usual~

u talk about gas so then i also talk about gas mah~
mana ada so expensive boss? ?
only rm1 for all round la~ 

if u cum look for me,i jus pump for u foc also no prb~
hahhaahaha~
lock nut up to u 1 lor~