18″ aluminium rims

Hello, I would like to upgrade to my Passat 18″ aluminium rim with 225 tyres (v+h). Are the 18″ wheels heavier than the standard Passat wheels (15″ steel, 205 or 195 tyres) ? If so, how strongly does this affect the acceleration and the maximum speed (e.g. with 102 hp or 115 hp gasoline) ?