Quote:
Originally Posted by mkoesel
I didn't watch the video yet, but does it explain why you wouldn't also want the larger size in front for the same reason? Or do we just assume that, because less sidewall will naturally impact ride quality, they use the smaller wheel up front as a compromise to minimize that consequence?
As I write this, I wonder if we might see equal diameter wheels on the AWD models. Though, I think Porsche uses the unequal sizes on their both their RWD and AWD 911 models. And come to think of it, IIRC, the AWD G8x mules have been using the same wheels as the RWD cars.
|
I'd say, two times no:
1/ the rear-axle mainly needs to deal with the lateral forces for propulsion, but the front-axle (certainly in combo with AWD) only deals with transversal forces. A higher side wall on the front provides a more progressive behaviour on steer-in. I remember going to a driving course of BMW and the instructors learned me that I provoked understeer by being too aggressive on steer-in. The higher side wall helps to be more progressive and it uses the grip limits to determine the tightest corner and renders a cleaner traject with less understeer.
2/ In the AWD version, the front axle becomes also responsable for the propulsion. In this case a stiffer side-wall makes sense. But seen the weight distri (which will be worse for AWD) and the potential understeer behaviour, I would bet that M prefers the staggered combo.