I should also add that wheel widths may be an issue on the rear though. I am pretty sure the wheel arch liners on M5s are designed to take wider wheels/tyres
last question!! my car is a pre facelift built dec 99. should the front abs sensors be blue or grey? also if the ring you describe is damaged does this mean i need a new hub? the abs sensor is not sending out signals its a blue one by the way.