Hey bro,
Im running 275/35/19 in front 305/40/19 in rear, currently on HKS adjustable springs at the lowest settings and I have not had any issues with the rock guards. If you plan on getting EVS fenders then you cannot use the front rock guards due to the way the fenders are made.
I agree with @Eastwood if the battery was not disconnected during the removal process this error could occur. Maybe try to disconnect the battery for 5 min and reconnect see if it resets the code. If not then i would maybe look on bimmerlink to see if you can reset through there.