Looking at info on the net it seems that the S3 saloon standard 19” wheels are forged and only weigh 9.7KG each whereas the optional 19” 5 arm design come in at 12.3kg and the 19” V spoke ones at 11.8KG. One would assume that the latter two are both cast? Has anyone had any issues with any of these wheels being buckled as on paper it appears the standard ones are lighter and maybe stronger??