Originally Posted by K3N R3D
What you said makes a lot sense intellectually, but consider this.
Since we all know RS is the performance version of standard Audi cars. And the CSL is the performance driven version of a standard M3. Why would BMW put 19" wheels on an M3 CSL if 18" wheels would perform better?
With ultra high performance tires, there is little difference between the handling potential of either 18s or 19s. The weight difference is negligible, as well, especially if, as on the E92, the larger wheels are forged. The larger wheels give more room for larger brakes. The smaller sizes have the advantage of a greater R-comp tire selection.