Run Flats to Non Run Flats

SteveSFO · 10-13-2014, 04:21 PM

Has any had any experience with swapping out their Run Flats with Non Run Flats? I am hearing conflicting statements. I understand that BMW calibrated the car to run flats and that going to non run flats will effect the handling of the vehicle.

I know that non run flats have a more compliant sidewalls. My concern is that if I swap over to non run flats, I'll negatively change the characteristics of the car.

Any insight would be appreciated.

horsepower_and_hounds · 10-13-2014, 05:28 PM

Switched them out on my 1 series and loved the change......just do it and don't look back

Delnari · 10-13-2014, 05:34 PM

Changed out my E92 335i when I had it. No negative change in the handling expect the ride was much smoother.

five3three · 10-13-2014, 08:45 PM

No issues whatsoever. I did that on my E90 335i and the difference was night and day without a single negative issue.

I really doubt that whole calibrated to the vehicle based on runflats part. I have also heard that BMW designs the wheels for runflats. Those are all things you'd hear from a dealer but are not true.

How exactly would a vehicle be calibrated to a specific kind of tire? Also, given that on the 228i/235i you have a choice of runflats or non-runflats on the exact same wheels, what is being calibrated?

The only thing that can be calibrated is your speedometer based on the size of tire you run. So, if you stick with the same size tires, your car will run the exact same.

A tire is a tire. Runflats run while they are flat. Non-runflats leave you stranded but run much smoother and quieter. It's as simple as that. The car has tire pressure sensors that work the same way without regard for the type of tire.

snodgrass23 · 10-13-2014, 09:34 PM

Quote:

Originally Posted by five3three

I really doubt that whole calibrated to the vehicle based on runflats part. I have also heard that BMW designs the wheels for runflats. Those are all things you'd hear from a dealer but are not true.

Yeap. They were trying to sell me on them too when I picked up my car, until I informed them my car did not come with them. The only thing to consider when switching tires is I think your rear wheels aren't as wide as if you'd have gotten the summer tires from the start, so that may affect the sizes you run when buying new tires.

SteveSFO · 10-13-2014, 11:47 PM

Thanks all. Appreciate the feedback and your experience.
In terms of calibration.... needed to hear from the community if there was any notable differences in terms of handling and performance.

Since when engineers determine spring rates, bushing hardness and geometry of the suspension, tires play a role in that. Since run flats have a stiffer and less compliant sidewall, my concern had to do with upsetting that calibration to a point where the ride and noise quality would be better with non run flats.

My appreciation to all who have made the swap and have not noticed any negative outcomes.

10-13-2014, 04:21 PM	#1
SteveSFO Enlisted Member 15 Rep 35 Posts Drives: '18 M2 Long Beach Blue Join Date: Oct 2014 Location: San Francisco Bay Area iTrader: (0)	Run Flats to Non Run Flats Has any had any experience with swapping out their Run Flats with Non Run Flats? I am hearing conflicting statements. I understand that BMW calibrated the car to run flats and that going to non run flats will effect the handling of the vehicle. I know that non run flats have a more compliant sidewalls. My concern is that if I swap over to non run flats, I'll negatively change the characteristics of the car. Any insight would be appreciated.
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10-13-2014, 05:28 PM	#2
horsepower_and_hounds Brigadier General 1836 Rep 4,203 Posts Drives: BMW Join Date: Aug 2012 Location: USA iTrader: (9)	Switched them out on my 1 series and loved the change......just do it and don't look back
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10-13-2014, 05:34 PM	#3
Delnari Major 255 Rep 1,040 Posts Drives: 2014 MG F22 Auto Join Date: Mar 2010 Location: Alexandria, VA iTrader: (2)	Changed out my E92 335i when I had it. No negative change in the handling expect the ride was much smoother.
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10-13-2014, 08:45 PM	#4
five3three Major 163 Rep 1,053 Posts Drives: m2c Join Date: Sep 2011 Location: VA iTrader: (3)	No issues whatsoever. I did that on my E90 335i and the difference was night and day without a single negative issue. I really doubt that whole calibrated to the vehicle based on runflats part. I have also heard that BMW designs the wheels for runflats. Those are all things you'd hear from a dealer but are not true. How exactly would a vehicle be calibrated to a specific kind of tire? Also, given that on the 228i/235i you have a choice of runflats or non-runflats on the exact same wheels, what is being calibrated? The only thing that can be calibrated is your speedometer based on the size of tire you run. So, if you stick with the same size tires, your car will run the exact same. A tire is a tire. Runflats run while they are flat. Non-runflats leave you stranded but run much smoother and quieter. It's as simple as that. The car has tire pressure sensors that work the same way without regard for the type of tire.
	Appreciate 0 Quote

10-13-2014, 11:47 PM	#6
SteveSFO Enlisted Member 15 Rep 35 Posts Drives: '18 M2 Long Beach Blue Join Date: Oct 2014 Location: San Francisco Bay Area iTrader: (0)	Thanks all. Appreciate the feedback and your experience. In terms of calibration.... needed to hear from the community if there was any notable differences in terms of handling and performance. Since when engineers determine spring rates, bushing hardness and geometry of the suspension, tires play a role in that. Since run flats have a stiffer and less compliant sidewall, my concern had to do with upsetting that calibration to a point where the ride and noise quality would be better with non run flats. My appreciation to all who have made the swap and have not noticed any negative outcomes.
	Appreciate 0 Quote