So the OEM parts have the following specs
Front 374X36
https://www.etkbmw.com/bmw/EN/search...iX/ECE/34_2471
Rear 345X24
https://www.etkbmw.com/bmw/EN/search...iX/ECE/34_2443
M5 is 395X36 front and 380X28 rear (steel) and 400X38 front 380X28 rear (ceramic)