43.4PSI is ridiculous imo. I'd never have any tyre pressures set that high on a road car.

As a very rough rule of thumb, and at that, one that doesn't really apply to run-flats, with their stiff sidewalls, the mass of the car in pounds, divided by the average tyre pressure, in PSI, is the area of the contact patch (in sq.in). So dividing this by 4, then again by the width of your tyre should yield the length of contact patch on the ground.

So it's easy to see, the higher the pressure, the less rubber is on the ground, although like i said, this doesn't really apply very well to runflats, and only makes any sense at reasonable working pressures where the tyre stiffness doesn't have much noticeable effect.

I'd be interested to see what the reason for pressures that high is.