From the 2003 USA Z4 Brochure....
Sport Package
For the ultimate in Z4 sport driving, both Z4 2.5i and 3.0i Sport Packages include the Driving Control "Sport" button for more spirited shifts, and a sport suspension. The Z4 2.5i package also includes 17 x 8.0 Turbine (Styling 106) cast-alloy wheels and 225/45R-17 run-flat tires, foglights and heated outside mirrors and heated windshield-washer jets. In the Z4 3.0i 18 x 8.0 front/18.5 rear Ellipsoid (Styling 107) cast-alloy wheels and 225/40R-18 front, 255/35R rear run-flat tires complete the package.