jonone

I have a msport e61 lci, and I've noticed it rolls a lot more since changing to non run flats, it kind of feels like the front and rear are slightly disconnected.
The tyres are a few months old and are 97y xl 245/40/18 sport contact 5s.
Any thing that wears out on e61s that cause this or mods I can do to help without ruining the ride.
The car has e60 m5 anti roll bars on it all ready.
Thanks.

JDeezyNYC

the non-run flats will be softer....more play, At higher speeds/lane-changing it's noticeable especially with the lifted center of gravity at the back of a wagon.

The tires are already on so that's that. You can stiffen up and/or lower the suspension.
strut tower bar , lower chasis brace aren't too expensive...

jonone

Thanks for the reply, Im surprised they have made that much difference, but I suppose run flats are like having super stiff sidewalls.
I don't want to lower it, so that's out! but I might try some bilstien dampers, there's a company near me that re-valves them to there spec.
I also might try the chassis braces that are std on cars with panoramic roof/ m5 bars.
Is there anything else that wears out?

rice_rocket88

I think it's the nature of your non-runflats and nothing is going to help. Even if you stiffen the car up more, it's the actual tire that is moving/bouncing your car around.

Although I have runflat 17" for winter tires vs 19" non runflats for the summer.. the difference in the contact patch and sidewall thickness makes them both seem to handle the same.. but the 19's even a little better (probably mostly because of the wider tire as well though).

OldSpool87

The feel also typically improves after a few 1000 miles when the tread blocks wear down a little. You could have the tires shaved to emulate this, but it seems an extreme measure for a street car. Besides what others have said about RF tires verus non, I think you may be experiencing a little tread block squirm.

jonone

Its a bit of a dilemma, I'm going to meet with a guy next week and he is going to drive my car and see what he thinks, he's the guy who does the revalved bilstiens.
He prefers normal tyres to run flats and says my dampers will be shot at 112k miles anyway, so I'm sure I know which way he will lean.
I've heard people say the oe dampers are shot by 60k but they feel ok to me? I wonder if this will help the roll? Or if it's just the effect of non run Flats?
I've got a pair of run flats I can put on the back to see if it goes away, if it does I'm left with the dilemma of do I keep normal tyres and try some bilstien b6 or do I sell the tyres and buy four new run flats but I'm back to crappy ride......

jonone

I got my local Indy to look at the suspension and they ended up changing the front and rear tc arms and the rear sub frame bushes + geometry, felt a bit better the steering has more weight so must have been out.
So I got some matching runflat rears of eBay and chucked all four back on and instantly back to feeling better.
Even though you feel the body roll you don't get that "flop" it transitions progressively.
It does ride a bit harder but not much, you notice it on really small hard stuff were its just the tyre acting as the suspension but any bigger stuff were you actually get into the spring and damper it doesn't feel much different.
I'm happy.
Going to try the pilot super sport zp next , as a new generation run flat they apparently ride really well.