there is a mark on the tire of how much pressure it can take at max,,1.9bar front 2.2bar rear is maximun,on my city,, i think 9bar is way to much,,the pressure gets higer when its get warmer outside and by riding the bike the tire gets a lot warmer,,and the origanal scooter tires are mostly of poor quality and are some times dangerus to use,,,cst is ok,,but il will change the tire to pirelli or continental..to ride safe when its wet outside.
