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Technical Topics Suspension / Chassis / Brakes Is the suspension different for cars equipped with run flats vs. those without?

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      12-03-2018, 05:14 AM   #1
cdgatti
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Is the suspension different for cars equipped with run flats vs. those without?

I see in the spec sheets for the new car that getting run flats or non-run flats will remain an option. Has anyone read whether some suspension components will be different to accommodate the different tires?
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      12-03-2018, 06:53 AM   #2
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I have not seen the specs, but I highly doubt they would change the suspension components. Take the non-run flats.
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      12-04-2018, 01:43 AM   #3
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I would very much doubt BMW would set up a different suspensions for vehicles ordered with non-runflat tyres. Overall it would represent a small fraction of its total worldwide sales and wouldn't be worth the engineering effort.

Plus what would happen in the scenario of someone switching from original non-runflats to runflats.

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      12-04-2018, 04:14 AM   #4
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Quote:
Originally Posted by cdgatti View Post
I see in the spec sheets for the new car that getting run flats or non-run flats will remain an option. Has anyone read whether some suspension components will be different to accommodate the different tires?
I see where you are coming from, would appear to be necessary in the fine tuning of suspension/tires. But no chance of different settings/calibrations, IMO. Years ago RFTs were so different in characteristics to standard non run-flat tires, we could feel a big difference in driving characteristics when we changed tire type. Tire characteristics are not as extreme these days, with vertical stiffness being much closer to each other.

Think about it this way, BMW do not change suspension calibrations for different wheel size options. BMW setup the chassis for the standard fit wheel size. I'd wager changing from 18" to 20" rims will be as big a change, (maybe more) as comparing a run-flat to a non run-flat of the same size.
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      12-04-2018, 05:09 AM   #5
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Thanks Pete - yea that makes sense, I hadn't considered the closing of the difference between the two tire types. Just know the E90 used softer rubber bushings in places due to the hard tires.
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      12-04-2018, 02:58 PM   #6
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Only thing I know of is that all season tires get a lower top speed limit.
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      12-04-2018, 08:36 PM   #7
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how often do we go 130 and find ourselves needing to go faster up to 155???
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      12-04-2018, 09:04 PM   #8
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Some people care especially you’re going to the track.
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      12-05-2018, 03:59 AM   #9
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Quote:
Originally Posted by cdgatti View Post
how often do we go 130 and find ourselves needing to go faster up to 155???
its not that. When I had my f30.... the performance summers it came with were much much stiffer than sport non run flats I eventually switched to. can't really get away with it if they are runflats, they will have stiff sidewalls to be able to keep riding if there is a flat.


Its not gonna make a difference going up to 150mph. Its for just every little crack and pothole in the road.

On the G20 it seems you have to get a m340i or a 330i with the dynamic handling package (diff/adaptive suspension etc) to be allowed to get non run flats. But at least you can get the donut with any car, and just swap out you tires after they wear out now
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