Regardless of the brakes the tyres will provide a given coefficient of friction (Cf).
Consider that this would be an equal force at each set of tyres, to quote Intensevil "(just before lock up).".
Therefore you have two cars going the same speed, but 1 weighing 1.5 times the other. The tyres are providing an equal force to slow each car, therefore the heavier one would take a greater distance to stop.
(ignore increased weight-> increased down force on tyre-> increased Cf for the moment)