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change of wheels / tyres - car feels slower
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08-29-2011, 07:08 AM | #1 |
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change of wheels / tyres - car feels slower
Hi, just changed over from 18 inch CSL reps with Falken 452 tyres (225/40/18 front and 255/35/18 rears) to 17inch BMW OEM 185 style wheels (Bridgestone Potenzas RE50 RFT 225/45/17s).
Now I may be imagining it but the car definately feels not as responsive / fast as with my previous set up. Maybe its just the tyres adjusting to the new camber/toe settings for the car? Any wheel/tyre experts care to comment? |
08-29-2011, 07:15 AM | #2 |
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Could be a large variety of factors so it's difficult to say what the cause is.
It could be wheel+tyre mass differences resulting in greater unsprung mass and needing more effort to turn. But, 18" cast csl reps would probably be similar in mass to OEM EH2 17" wheel. However the 17" RFT tyre might be heavier than the nonrft 452s. Hard to say without knowing how much each component weighs. Otherwise it could just be the friction between tyre and road causing it to feel slower. Maybe the stock RFTs have a greater frictional coefficient than the Falkens? |
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08-29-2011, 03:51 PM | #3 |
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We're still waiting for you to post that magic link????
http://www.e90post.com/forums/showthread.php?t=576567
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08-29-2011, 10:23 PM | #4 |
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I think its possible you have added up to 2kg per corner. Stock BMW rims are very heavy and runflats will also add an extra 0.8 ~ 1kg for each tyre. I think there is an effect on performance, but probably hard to notice unless you test it against a stopwatch.
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08-30-2011, 04:19 AM | #5 | |
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Quote:
Likewise rolling diameter is changed by a trivial amount, and if anything the car would be a trifle lower geared withe the 17's. I'd also think rolling resistance is less with RFT's - especially as the Falken's are not known for that quality and tend to have a wider tread vs rim width than Bridgestones also. Makes no sense
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17 F87 M2 Pure - long beach blue 10 E91 320d LCI - space grey - black dakota - steptronic - innovations - 157s - front PDC - Konis 99 BMW Baby Racer - red; 05 Renaultsport Clio 182 Cup - French Racing Blue - Konis - Eibachs - Remus - Turinis |
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08-30-2011, 04:51 AM | #6 |
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I've had my 194M 17" wheels on the scales and they weighed 12.8kg (F) and 13.1kg (R). The figure from the BMW catalogue of 10.36kg isn't very accurate in the case of my wheels.
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08-30-2011, 03:06 PM | #8 |
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08-30-2011, 07:19 PM | #9 |
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KU31s were scary compared to Michelin Pilot Exaltos on my Renault.
Run away. Far away.
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John
17 F87 M2 Pure - long beach blue 10 E91 320d LCI - space grey - black dakota - steptronic - innovations - 157s - front PDC - Konis 99 BMW Baby Racer - red; 05 Renaultsport Clio 182 Cup - French Racing Blue - Konis - Eibachs - Remus - Turinis |
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08-31-2011, 02:21 AM | #11 |
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I'm content with my KU31s. Good enough to 320i power and daily driving. However they are quite noisy and on the track my RFT PS2s performed better. In fact my RFT PS2s were generally better than Ku31s..
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08-31-2011, 03:24 AM | #12 |
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Shit if rft's are better, I still say super sports all the way FTW
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08-31-2011, 05:41 AM | #13 | |
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Seriously though, the Renault is the complete opposite of the BMWs so I probably shouldn't extrapolate.
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John
17 F87 M2 Pure - long beach blue 10 E91 320d LCI - space grey - black dakota - steptronic - innovations - 157s - front PDC - Konis 99 BMW Baby Racer - red; 05 Renaultsport Clio 182 Cup - French Racing Blue - Konis - Eibachs - Remus - Turinis |
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09-01-2011, 02:06 AM | #16 |
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Taming KU31s = Respect
[Not having a dig, wasn't party to MDTC times ]
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John
17 F87 M2 Pure - long beach blue 10 E91 320d LCI - space grey - black dakota - steptronic - innovations - 157s - front PDC - Konis 99 BMW Baby Racer - red; 05 Renaultsport Clio 182 Cup - French Racing Blue - Konis - Eibachs - Remus - Turinis |
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