E9* 330i touring tyre help

[Zippee]

I need to replace 1 of my 18" rears, currently a Pilot sport 3 run flat - the other 3 corners have around 6mm left.
I can either opt for a single pilot run flat at just over £200 for the corner.
The other option is to bite the bullet (cheaper on a per corner basis) and replace all 4 for non run flats. Pilot sport 3s come in about £360 all in or Uniroyal Rainsport 3s a little cheaper.

Just wandering what people recommend on this era (2007) of 3 series or thoughts on the best way to go.

[Zippee]

Thanks all – that’s a good shout on the change to non RF and selling the remaining 3 part worns, though I’m not keen on PWs for myself.
I’ll look up the Contis, any thoughts on the rainsports or non run flat versions of the Pilot sports?