I'm replacing the tire on the rear of my 2007 LT and just checked the ABS Air Gap. The gap is 006-007", far tighter than the .018 - .022" in the maintenance manual. Should I try and increase the gap? I'm assuming you add a shim, but can I use just apiece of sheet metal as a shim or do I go to Mother BMW for one? I don't see in the manual if it say how to adjust the gap, just that it should be adjusted! Thanks.