Originally Posted by CC 330i
It's really hard to say. One person said that they didn't notice any adverse effects from going to 19s with non run-flats. Run flats are heavier by up to 10 pounds per tire (from what I have heard) so it stands to reason that less unsprung weight would make for a better ride.
But being that the suspension in the E90 is apparently tuned with run-flats in mind, it's hard to say what a lighter wheel/tire combo would do. I know that the ride on the E90 with run-flats is much better than it is in the Mini and the 5 series with run-flats.
Conventional wisdom is that less unsprung weight will definitely help the ride.
Holy crap, are they really heavier by up to 10 pounds each?? I'm definitely switching to non-runflats when these stock tires are done. 10 pounds at each corner will make such an awesome difference in handling. I guarantee it.
Also, altho I don't have specific experience with using non-runflats on this car, on paper the non-runflats must ride more comfortablly / less harsh than the runflats because the runflats have a much much stiffer sidewall.