[msej449]

When you change from one brand of runflat to an entirely different brand of non-runflat, how do you know that the improvement you feel is wholly down to the 'runflatness' of the previous tyre? It could just as well be due to a change of brand. Has anyone changed from exactly the same tyre in runflat form to non-runflat?

Also bear in mind there are around eight different variants to the PZero, including the 'old' PZero and the 'new' PZero, so this can make comparisons different.

I don't doubt there's some difference in handling with non-runflats but I wouldn't necessarily ascribe all of the improvement to swapping. Basically, I suspect that there are much better runflats for the 2 Series than the Pirelli PZero out there (as @3rdcoast228i reports above).

When I worked for Pirelli, the PZero was primarily designed for fairly heavy performance cars (think Aston Martin, AMG etc.). It doesn't seem to suit lighter-weight models at all, so I'm not surprised that a switch to another brand would be an improvement, runflat or not.