Yeah the 18s just seem a bit small ... even though the slk is a small car.
Of course the brakes look that much bigger on 18s
I went down to 18s because of tire selection. While there are some R compound tires in 19s there is more selection for 18s. Also for drag slicks I don't think anything is made for our sizes in 19s.
Right now even the Michelin cup tires don't give enough traction on launch.