[quote=”macmacaman” post=252]For those of use running stock run-flats on E90’s, what tire would you recommend changing to? I am perfectly fine with going to non-run flats, but I have heard, apocryphally, that E90 suspensions are tuned for the stiffer run-flats. Is there someting intrinsic to the stock E90 wheels that will only accept run-flat tires?
I have 17k miles on my tires, well above the wear bars, but the BMW service techs are starting to harangue me about wear on the outer edge of the tires, suspecting misaligned camber. I actually think it is wear from 5 auto crosses and a couple of track days.[/quote]
The newer BMW non-M suspensions are tuned for the stiffer sidewall run flat tires. They do that by softening up the bushings on the control arms (wishbones and tie rods). Soon after I bought the car I changed from the stock 135i control arms to the M control arms. The ride got noticeably harsher. Then when the RFT were toast, I went to regular tires. The ride returned back to before I swapped out the original control arms. The difference was that the stiffer control arm bushings provided a better feel and less slop in cornering. You would be surprised how soft the stock bushings are to make up for the RFT.
You can use either RFT or regular tires. If you go with regular tires you should get a mobility kit like they have on the M cars (as they have regular tires and do not have a spare).