The PS2 runflats for the 18" wheel sizes are actually very impressive.
When I bought my 335i, coming from a 06 Volvo s60r and 08 M3 sedan with non runflats, my plan was to change the 335i to non runflats as well and buy a m mobility kit and chance it like on the M3.
However, my car came with the PS2 runflats which rode and handled so good (none of the skittering over uneven pavement and crashing over small bumps like bridgeston RFTs) I stuck with the PS2 RFTs.
Unfortunately the PS2 are just as expensive as the bridgestone RFTs
. But the ease of not having to pull over on the side of a busy highway during rush hour to pump seal a flat gunk into my car or worse, waiting a hour for a tow truck definitely is worth something for me.
Before I tried the PS2 RFTs, I would be all for BMW decreasing the already small e90 trunk to make room for a spacesaver spare but now I am not so sure.