Running large sticky tires on the rear helps prevent the rear tires from locking up on initial braking.
If you dont run a prop valve With stock size tires though the rears will skid before the front discs start to work.
That's precisely the point. A drag car has a bigger stickier contact patch in the rear, so you can increase the braking force back there.
Or rather, decrease the front pressure. Drag car usually has skinnies up front with a smaller contact patch that would be prone to skidding if to much pressure is applied. Also drag cars usually have improved weight distribution to the rear as well.
At least that's the reasons that I told.
