Look at it this way--if you can slam on the brakes and the ABS kicks in, to decrease the stopping distance anything significant, increase the grip of the tires.

Assuming braking activates ABS:
1) Current brakes, slotted rotors, high friction pads and stainless brake lined results in more stopping power sooner, some decrease in stopping distance-- low expense.

2) Bigger brakes, bigger pad surface area results in more stopping power sooner and some decrease in stopping distance--greater expense.

3) Bigger brakes, bigger pad surface and greater traction tires results in more stopping power both sooner and ongoing and greater decrease in stopping distance.

1 and 2 will deliver similar results.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas