Mycroft said:200lb downforce gives 280lbs of sideways resistance on those graphs [roughly]...
At 400lbs there is 560lbs the ratio of the difference remains the same, however with every doubling on the downforce [200-->400] there is doubling of the grip [280--->560]
Can you see that? As one doubles so does the other, the ratio of adherence remains at 1.4 / 1.5 but the grip doubles as the weight doubles.
These graphs were presented as proving that the grip lessens immediately from 1kg... they do not do this they clearly show what I have said all along, 'only after the tyre reaches its optimum adherence/weight limit will the tyre start to show diminishing returns for the weight applied.
This is the first post in here that makes some sense (to me)