1. Easiest way to lower car is smaller diameter rims and tire
2. If you want to reduce the space between the top of the tire and the wheel well you can cut the springs. This will alter the cars handling and increase tire wear because there is no adjustment for chamber as the car comes from the factory. Use the search box in upper right corner of the forum to find many posts on camber adjustment. There are also rubber pads, Mercedes calls then isolators, on the top of the springs which come in different thickness. The max difference between thick and thin is about a half inch. Part numbers are 210-325-01-84, 210-325-03-84, 210-321-02-84, 210-321-04-84, 210-321-05-84. I think 210-321-01-84 and 210-321-03-84 would also work on our cars, but they are not listed on the Mercedes parts catalog for the SLK model.