Pirelli P Zero Corsa diameters...
Front: 255/35-ZR19 measures at 25.94" OD
Rear: 285/30-ZR19 measures at 25.88" OD
Unloaded but inflated and mounted. The true rolling circumference would be fractionally less than Pi times the OD due to the tire flattening against the road surface when loaded.
2015 BMW M5 Sedan M-DCT w/Competition Pkg and Carbon Ceramic Brakes, Driver's Assistance, and Executive Pkgs, B&O, Alpine White / Sakhir Orange and Black Full Leather, lots of carbon fiber, and a Trunk Monkey called "Der Stig".