hi guys, i have a 530d with full m5 aero kit on it, i have just bought some 20" m5 style wheels 245/35/20 fronts 8.5" 275/30/20 9.5 rears, how much can i lower it? some people say 30mm some 50mm, i want it as low as possible but dont want any rubbing and if i have a full car load would it rub? any info would be great