Quote by R33:"Now the heaver car will have more weight on the tyres. This means that more braking force can be applied before lock up. Therefore the heavier car is capable of more braking force before reaching its maximum which occurs just before lock up. It is because of the fact the heavier car can apply more force that it will stop quicker."
Dude, i think what you are refering to is pressure....that because of the extra weight, there is more pressure per square inch of the tire's contact patch compared to the lighter car, and hence should be able to apply more force without reaching the grip limit and locking up.
But i think you forgot to factor in that while there is more weight and pressure on the tires to give it an increased grip limit, there is also that extra weight which will overwhelm the grip as well.
Put simply...if what u said were true.....F1 cars would weigh 10 tonnes and wear 175mm tires.... but we dont see that happening dont we?