Are there not two sizes of tires on a Diablo or a Murci? My rear tires are larger than my fronts even though the wheels are 19" each. Last I knew, the ABS system senses and compares the rotation of all tires to inform you of a tire that is low on pressure, for traction control, and equalized braking. Does the Impala have different sized tires? This would change my opinion too. I think that ABS is more trouble than it's worth. My $.02
Jim