I realise this is an old thread but having fitted a new set of RE003s on my 335i I thought I would give an updare. The old front tyres were Nitto 830s and out back were a set of RE050 run flats. First impressions are that the front end is a lot more precise, turn in is noticeably more direct and I feel like it goes were it should now. The rear has a bit more compliance but grip wise it seems to be at least as good as the 050s maybe even better. I never really felt I could trust the run flats on anything other than bowling green smooth roads, they had a lot of harshness and the ride was jittery. On a typical NZ road with a few undulations and irregularities mid corner the 003 is just so much more predictable. I was considering S001s but having had them on my 335i on the original 17s I didnt think they were appreciably better than the 003s, not a fair comparison I know as one is a 40 series and one is 35. I suspect on a track the S001 would show its advantages. To sumarise I now have much sharper and more accurate turn in, the car feels more predictable and overall grip levels in the dry are higher especially up front. Later this week I am driving another 335 with 19s and its running some Falkens, I will report back when I have given it the 48 corner test.