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11-18-2012, 12:50 AM | #1 |
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NRFTs better performance?? Not to sure about that!
Ok, so only being new to the whole run flat saga, I read as much as I could on ditching the Rft's on my 135i with the idea I would also go get some 19in VMR 718s with Michellin PSS (225/35/19_255/30/19) as all I could read was how terrible the RFT's were and how better the feel and ride was with Non Rft's.
Though after having the new set up on the car for a week, I feel that, yes, it is quieter, however performance has been altered massively, to the point where I am careful on how I drive the car. The car feels floaty and unstable. From what I have read, this is the normal for most first impressions for the reasoning of a weaker sidewall. Though I am now at the point where I may rid of the PSS and get some 19in RFts to gain back the performance. BMW remark 'all of our vehicles that use Run-flat technology have their suspension and braking components set up to accommodate Run-flat tyres. Should you decide to change to non Run-flats, it may alter the driving and handling characteristics of your vehicle. It is for this reason that this modification is not recommended by BMW as a manufacturer.' and may I add this is the same for most tire expert websites. I run the tire pressures of 160KPA (40PSi) all round and though I am running 19's the rolling diameter difference is very minimal (1%) to the OEM RFTS which were running on the 261 Msport rims. Additional to this the car is stock with the stock msport suspension. How can I get back performance, will different pressures or springs or whatever help?
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Last edited by totobmw; 11-18-2012 at 05:58 AM.. |
11-18-2012, 05:52 AM | #3 |
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That is an extremely tall rear tire... Can't be within 1% of the OEM tire.
I just did the calculation and a 255/40/19 is over 8% different than the OEM 245/35/18. There is your float.
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11-18-2012, 05:57 AM | #4 |
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geez, error, have readjusted, is F 35_ R 30
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11-18-2012, 06:03 AM | #5 |
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When I had my PSS on my STI (275/35/18 all around) I found 40 to be too high of a pressure. I was getting excessive wear on the middle of the tread patch. Try a bit lower?
When you say floaty, does it feel like suspension? Does it feel extra bouncy over bumps? Too high of a pressure might make it too firm. Did you have an alignment done lately?
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11-18-2012, 06:20 AM | #6 | |
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Quote:
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11-18-2012, 07:00 AM | #7 |
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Your suspension bushings are set up for run-flats, replace them with stiffer bushings and your problem will disappear. That is the only issue. And honestly, when i changed over, i didn't notice a real difference other than I now had more straight line traction.
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11-18-2012, 10:56 AM | #8 |
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Plenty of cars come off the truck with bogus alignments. At least with some of the Japanese cars.
Also, the alignment specs are pretty wide with toe angle, +\- .25 if I read the spec sheet correctly.
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11-18-2012, 03:15 PM | #9 |
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Have you attempted to do this? Or is this the norm.
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11-18-2012, 03:34 PM | #10 |
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I have not done it yet, but it is pretty normal. Most people upgrade to the M3 links and bushings because of this.
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11-18-2012, 07:06 PM | #11 |
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Not sure this helps but for "normal street driving" i have found that adding the M3 FSB and running Yokohama ADO8's on my car with VMR 19" rims it has improved handling and ride..225F/255R..The GREAT grip of the ADO8 ans very stiff sidewall has improved turn in as well,,,also they have worn very well for me..have them on the car now a year and a half...I have Michelins on my DD and indeed they do have sidewalls that are a tad soft,
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