Tyres.co.uk lists Michelin Pilot Sport 4 S and Pirelli P Zero as standard fitments for the BMW M6 F13 Coupé (2012-2018) on 19-inch wheels, at 265/40 ZR19 102Y XL front and 295/35 ZR19 104Y XL rear. Check registration and wheel selection before purchase.
For BMW M6 tyre size, check the BMW M6 tyre pressure sticker located on the driver side door. The sticker contains front and rear sizes, pressures, loads and speeds. This sticker must be referred to, because the M6 spans multiple generations and wheel types.
For the BMW M6, it is not necessary to purchase all four new tyres. As the vehicles are all rear wheel drive, and do not have xDrive that matches the circumference, the owners have the opportunity to continue with staggered fitment and keep each axle matched. As per the UK safety recommendation, if two new tyres are fitted, they must be fitted to the rear axle.