"Tyre weight, sidewall stiffness, carcass construction and all the rest do not generally affect the handlng characteristics of a tyre"

I totally disagree. You are telling us that sidewall stiffness does not "generally" affect the handling characteristics of a TIRE? Total Bullshit.

So, if it's all in the 'so called' tire pressure, then why did they need to invent run flats? That tire depends ENTIRELY on it's sidewall stiffness and drives just as well with NO pressure as it does with pressure, you just can't go as fast.

Also, as long as you don't drive a North American car with Super bubbly assed tires on it, you definately feel a difference between tires with stiffer sidewalls or softer sidewalls. The stiffer sidewall doesn't allow the tire to roll laterally from under the rim, which most definately affects the cars handling.