Runflats improve performance?

Antartic · 02-14-2013, 01:52 PM

I went to the dealer to see what it would take to swap my runflats for non-run flats.

The dealer said that runflats are better for performance for my 335i because the whole handling dynamics of the car was designed based on runflats. He added that the stiffer sidewalls of runflats help maintain their shape during hard cornering.

He agreed that non-runflats are quieter and provide a comfortable ride, but if it is performance that I am looking for (I am) then runflats are my best choice.

Do you guys think he is BSing me, or does he have a point?

ctuna · 02-14-2013, 01:58 PM

Do a search there are so many threads on this.
I can tell you my friends that race will not have run flats
on there cars.

Tom K. · 02-14-2013, 02:01 PM

1. Your dealer will only sell you RFTs so they have a financial interest here. Check out tirerack.com for more info.
2. Which RFTs and which non RFTs are you considering? There is a big variation among each so make sure you are comparing apples to apples.
3. In general, I prefer the ride and price of non RFTs. Handling is largely dependent on tread design and other factors - so some RFTs will outhandle some go-flats and vice-versa.
4. You'll probably get better responses in the Wheel/Tire forum:

http://www.e90post.com/forums/forumdisplay.php?f=12

Tom

ChipB · 02-14-2013, 02:07 PM

Is he BS-ing you ? No, and yes.

No BS - the car is deigned with particular tire dynamics in mind, so if by optimal "performance" he means handling exactly as designed by the factory - then the stock RFs are it and anything else will be a little off.

But I call BS because your perception of "performance" is likely different than the factory's. As you've noted RFs tend to be noisy, and many think they are a bit "harsh" due to the stiff sidewalls. This hashness means more energy from bumps is transmitted through the sidewall to the wheel and into the suspension. Consequently many have reported that switching to non RF's makes for a more enjoyable ride. And any detrimental effect on handling (due to the slightly softer suspension system that you have with non-RFs in the mix) is so slight as to be negligible. Finally the actual performance available on non RFs in the after-market can exceed the stock RFs in grip, cornering, wet and dry traction, etc.

Bottom line is it's impossible to say whether changing will improve or worsen handling - you need to let us know specifically which model of tire you're looking at. One thing I wouild recommend is since your car originally came with summer tires (I believe), don't comprimise with all-seasons, but rather stick with summer tires in summer and winter tires in winter.

FlowState · 02-14-2013, 02:07 PM

it is true that the car's suspension was designed around being able to use runflats, however it will not make it perform any better by using them.

Runflats have their own flaws, that the suspension was designed to make up for.

Not having the flawed tires = better performance.

sohlman · 02-14-2013, 02:16 PM

If the run flat tyre was a better performing tyre then the BMW M division would use them on the M3. They chose non run flat tyres. Enough said.

There is a number of reasons for run flats the main being weight saving of a spare, jack etc which helps co2 and emissions and safety in the event of a blow out

raj55 · 02-14-2013, 02:28 PM

The run flats are great for high speed cornering ability and stability on the road when you are trying to avoid an obstacle but then you sacrifice ride quality since you have a less smooth ride (judder and bumps on the road are more easily felt with run flat). Personally, I feel that run flats are great for more aggressive driving style and are more safe if you have a sudden puncture during motor way driving. You are likely to have better control over your car in such a scenario. My summer tyres are run flat (faster speed on the road) and the winter tyres are non run flat (slower speed on ice and snow). So not every thing is bad with run flats.

bender rodriguez · 02-14-2013, 02:39 PM

I don't like them because because places wont patch them..

Antartic · 02-14-2013, 03:03 PM

thanks for the replies guys. the current run flat tires that I have are performance summer Michelin Pilot Sport PS2ZP.

I was planning to get Pirelli P Zero Rosso.

I am not worried about the harshness of the ride or how easy it is to patch it- I want to make sure the car retains (or improves) the driving dynamics that it current has with RFT tires.

Most of the threads I searched for tires talk about the harshness and noise. Very few had any good discussions of performance (as far as I saw).

BEAR-AvHistory · 02-14-2013, 03:21 PM

Ask the dealer if the factory puts RFT on the M3.

edirtaynine · 02-14-2013, 03:27 PM

Quote:

Originally Posted by Antartic

The dealer said

theres the start of the problem right there

Meeni · 02-14-2013, 03:34 PM

Quote:

Originally Posted by Antartic

The dealer said that runflats are better for performance for my 335i because the whole handling dynamics of the car was
designed based on runflats.

That is true, but it is not really an "advantage". Because RFT are so bad, the shocks have to overwork.

Quote:

He added that the stiffer sidewalls of runflats help maintain their shape during hard cornering.

If that was the case, non-RFT super summer performance xtreme add your superlative Michelin Pilot tires would be as stiff as RFT. They are not.

All I know, is that I preferred the handling of the non-RFT tires by several parsec. It does feel a bit soft on the stock shocks, but it has very predictable limits, RFT tend to loose it more abruptly, I don't like that.

335BBS · 02-14-2013, 04:10 PM

Quote:

Originally Posted by Antartic

I went to the dealer to see what it would take to swap my runflats for non-run flats.

The dealer said that runflats are better for performance for my 335i because the whole handling dynamics of the car was designed based on runflats. He added that the stiffer sidewalls of runflats help maintain their shape during hard cornering.

He agreed that non-runflats are quieter and provide a comfortable ride, but if it is performance that I am looking for (I am) then runflats are my best choice.

Do you guys think he is BSing me, or does he have a point?

WRONG. Salesman is full of it. Sidewalls being this stiff HURT handling. At city speeds they feel more responsive but at speed they are not. Try going through a corner and hitting a bump......car jumps sideways as sidewall is so stiff. We need Captainaudio to explain slip angles again. Sidewalls need to flex more that rft to maintain grip.

Dark_Knight_335 · 02-14-2013, 04:49 PM

Your dealer handed you a line of bullshit. They are expensive and OEM for any dealer. I swapped my RFTs years ago and sold them. Never looked back.

derrick603 · 02-14-2013, 04:57 PM

Quote:

Originally Posted by 335BBS

WRONG. Salesman is full of it. Sidewalls being this stiff HURT handling. At city speeds they feel more responsive but at speed they are not. Try going through a corner and hitting a bump......car jumps sideways as sidewall is so stiff. We need Captainaudio to explain slip angles again. Sidewalls need to flex more that rft to maintain grip.

Agreed. Keep in mind that the sidewalls of an RFT are designed to be stiff for run-flat purposes, not specifically for performance. There is no reason that a max performance non-RFT could not be designed with the same level of sidewall stiffness if it was an advantage.

MrDummy · 02-14-2013, 04:59 PM

I want to switch but I only have stock 16" tires so its not worth it IMO.

Until I figure out what rims to get to replace current ones. I don't know how big I can go? Would 18" RIMs be the largest I should go with?

335dFan · 02-14-2013, 05:37 PM

Quote:

Originally Posted by Antartic

I went to the dealer to see what it would take to swap my runflats for non-run flats.

The dealer said that runflats are better for performance for my 335i because the whole handling dynamics of the car was designed based on runflats. He added that the stiffer sidewalls of runflats help maintain their shape during hard cornering.

He agreed that non-runflats are quieter and provide a comfortable ride, but if it is performance that I am looking for (I am) then runflats are my best choice.

Do you guys think he is BSing me, or does he have a point?

This may be the default dealer SA response, since the dealer near me said almost the same words ("whole package was designed as a system and the DSC and everything else is all engineered to work together"). Looking at it from the dealer's point of view (forget about the financial aspects for a minute), they may be weary of customers making their own changes outside of the BMW party line, and then running to the dealer when something is not right, and it relates to something the customer did outside of BMW's comfort zone. There is always some consequence for each of our choices. Nothing wrong with that.

I just listen to all sides, read a lot on the forums and other places, make my choices in as informed a way as I can, and accept the results and consequences, or trip up and try something else. On the tire issue, I ended up just putting RFT Blizzak LM-25 on for the cold season, and I will probably put non-RFT on when the warm weather comes back, even though I have a lot of tread left on the OEM RFT all-seasons. The logistics influenced me, because I want to leave the winter tires on the OEM wheels, and the OEM RFT all-seasons won't fit on the new wheels I want, so I decided to bite the bullet. Now the only decision is whether to buy a fifth wheel and tire, or get one of those aftermarket spares.

j2m · 02-14-2013, 06:16 PM

Your dealer is full of SHIT!
**tell them I said so**

tunachris · 02-14-2013, 07:27 PM

Best move I ever made was switching to Michelin Pilot Super Sport non run-flats. Only problem is I go through tires at a horrendous rate. I get about 25,000 on the fronts, and at best maybe 12-13K on the rears.

AWil335i · 02-14-2013, 07:42 PM

The PS2 RFTs aren't bad, but I just switched to Pilot Super Sports and they definitely have more grip.

chromisdesigns · 02-14-2013, 10:35 PM

Quote:

Originally Posted by BEAR-AvHistory

Ask the dealer if the factory puts RFT on the M3.

+1000! That's the story, right there...

I hated the OEM Bridgestone bricks on my 2008 335i -- got rid of them just as fast as I could. I particularly disliked the way they hop on bumpy corners, the car literally went sideways when the tires got air in the corner.

Since driving around the SF Bay area is a study in lousy road surfaces, I am MUCH happier since I sold them to a guy looking for lease return tires and got some **real** tires on the car.

Not to mention, the non-runflats are cheaper and last half again as long in addition.

driverman · 02-15-2013, 12:10 AM

This statement from the OP is true: "the whole handling dynamics of the car was designed based on runflats".

It's also true that the M3 doesn't use RFT's.

So how would our sport suspensions be different if BMW designed them for non RFT's? Does anyone know? I've read BMW used softer bushings to make up for the stiff sidewalls.

After running original OEM Bridgestone RFT's then PS2's then DW's, I can tell you they all feel quite different. I can also tell you that DW's are 30 pounds lighter (as a set) than RFT's.

Captain Audio posted good stuff on slip angles that explains why RFT's don't handle better even though they have better steering response.

02-14-2013, 01:52 PM	#1
Antartic Second Lieutenant 97 Rep 293 Posts Drives: F80 M3 2018 Join Date: Sep 2010 Location: USA iTrader: (0)	Runflats improve performance? I went to the dealer to see what it would take to swap my runflats for non-run flats. The dealer said that runflats are better for performance for my 335i because the whole handling dynamics of the car was designed based on runflats. He added that the stiffer sidewalls of runflats help maintain their shape during hard cornering. He agreed that non-runflats are quieter and provide a comfortable ride, but if it is performance that I am looking for (I am) then runflats are my best choice. Do you guys think he is BSing me, or does he have a point?
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02-14-2013, 01:58 PM	#2
ctuna Lieutenant General 2098 Rep 13,467 Posts Drives: 325xi 06 wagon MT Join Date: Jan 2010 Location: Santa Cruz, Ca iTrader: (0)	Do a search there are so many threads on this. Do a search there are so many threads on this. I can tell you my friends that race will not have run flats on there cars.
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02-14-2013, 02:01 PM	#3
Tom K. Major General 125 Rep 5,626 Posts Drives: '07 328iT, '13 Boxster Join Date: Mar 2008 Location: Maryland iTrader: (0)	1. Your dealer will only sell you RFTs so they have a financial interest here. Check out tirerack.com for more info. 2. Which RFTs and which non RFTs are you considering? There is a big variation among each so make sure you are comparing apples to apples. 3. In general, I prefer the ride and price of non RFTs. Handling is largely dependent on tread design and other factors - so some RFTs will outhandle some go-flats and vice-versa. 4. You'll probably get better responses in the Wheel/Tire forum: http://www.e90post.com/forums/forumdisplay.php?f=12 Tom
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02-14-2013, 02:07 PM	#4
ChipB First Lieutenant 57 Rep 374 Posts Drives: 2015 M4, 2022 X5, 2014 X5 Join Date: Nov 2010 Location: Vero Beach, FL iTrader: (0)	Is he BS-ing you ? No, and yes. No BS - the car is deigned with particular tire dynamics in mind, so if by optimal "performance" he means handling exactly as designed by the factory - then the stock RFs are it and anything else will be a little off. But I call BS because your perception of "performance" is likely different than the factory's. As you've noted RFs tend to be noisy, and many think they are a bit "harsh" due to the stiff sidewalls. This hashness means more energy from bumps is transmitted through the sidewall to the wheel and into the suspension. Consequently many have reported that switching to non RF's makes for a more enjoyable ride. And any detrimental effect on handling (due to the slightly softer suspension system that you have with non-RFs in the mix) is so slight as to be negligible. Finally the actual performance available on non RFs in the after-market can exceed the stock RFs in grip, cornering, wet and dry traction, etc. Bottom line is it's impossible to say whether changing will improve or worsen handling - you need to let us know specifically which model of tire you're looking at. One thing I wouild recommend is since your car originally came with summer tires (I believe), don't comprimise with all-seasons, but rather stick with summer tires in summer and winter tires in winter. __________________ F83 M4 convertible, F15 X5 xDrive35i Previous: E93 335i, E36 328iC, E28 528e, E21 320i
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02-14-2013, 02:07 PM	#5
FlowState ///M Driver 112 Rep 1,973 Posts Drives: 07 JB E90 335, 20 TRM F97 X3M Join Date: Jan 2011 Location: Chicago, IL iTrader: (4)	it is true that the car's suspension was designed around being able to use runflats, however it will not make it perform any better by using them. Runflats have their own flaws, that the suspension was designed to make up for. Not having the flawed tires = better performance.
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02-14-2013, 02:16 PM	#6
sohlman Second Lieutenant 11 Rep 208 Posts Drives: E90 330iSE Join Date: Jan 2013 Location: Surrey iTrader: (0)	If the run flat tyre was a better performing tyre then the BMW M division would use them on the M3. They chose non run flat tyres. Enough said. There is a number of reasons for run flats the main being weight saving of a spare, jack etc which helps co2 and emissions and safety in the event of a blow out __________________ E90 330i SE Auto Graphite Grey Metalic
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02-14-2013, 02:28 PM	#7
raj55 First Lieutenant 28 Rep 303 Posts Drives: E91 2009, 320i Join Date: Mar 2009 Location: SWEDEN iTrader: (0)	The run flats are great for high speed cornering ability and stability on the road when you are trying to avoid an obstacle but then you sacrifice ride quality since you have a less smooth ride (judder and bumps on the road are more easily felt with run flat). Personally, I feel that run flats are great for more aggressive driving style and are more safe if you have a sudden puncture during motor way driving. You are likely to have better control over your car in such a scenario. My summer tyres are run flat (faster speed on the road) and the winter tyres are non run flat (slower speed on ice and snow). So not every thing is bad with run flats.
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02-14-2013, 02:39 PM	#8
bender rodriguez Banned 155 Rep 1,995 Posts Drives: Audi Join Date: Mar 2011 Location: CA iTrader: (1)	I don't like them because because places wont patch them..
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02-14-2013, 03:03 PM	#9
Antartic Second Lieutenant 97 Rep 293 Posts Drives: F80 M3 2018 Join Date: Sep 2010 Location: USA iTrader: (0)	thanks for the replies guys. the current run flat tires that I have are performance summer Michelin Pilot Sport PS2ZP. I was planning to get Pirelli P Zero Rosso. I am not worried about the harshness of the ride or how easy it is to patch it- I want to make sure the car retains (or improves) the driving dynamics that it current has with RFT tires. Most of the threads I searched for tires talk about the harshness and noise. Very few had any good discussions of performance (as far as I saw).
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02-14-2013, 03:21 PM	#10
BEAR-AvHistory 2020 Z4 M40i - 2022 M4C Convt 3174 Rep 5,264 Posts Drives: 2020 Z4 M40i - 2022 M4C Convrt Join Date: Jun 2011 Location: Raleigh, NC - OIB, NC iTrader: (0) Garage List 1965 COBRA (FFR rep ... [8.57] 2023 Jeep Wrangler ... [4.75] 2009 Yamaha V-Star [0.00] Cars 2-BMW, 2-FORD, ... [0.00] 2023 Ford Expeditio ... [0.00] 2020 Z4 M40i [10.00] 2022 BMW M4C [7.25] 1998 FORD Ranger 4X4 [0.00]	Ask the dealer if the factory puts RFT on the M3. __________________ Kevin Dravit Gray, Black Leather, Moonlight Roof, Red Calipers 2022 M4C - 2020 Z4 M40i - 2023 FORD Expedition XLT Max 4X4 400BHP - 2009 V-Star - 1998 Ranger 4X4 5MT - 1965 Cobra (R) 5MT - 2023 Jeep Wrangler Sport S 6MT
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02-14-2013, 04:49 PM	#14
Dark_Knight_335 Came to the N55 Darkside 1139 Rep 12,740 Posts Drives: 2011 335 E93 M-Sport Join Date: May 2010 Location: NY/NJ iTrader: (28)	Your dealer handed you a line of bullshit. They are expensive and OEM for any dealer. I swapped my RFTs years ago and sold them. Never looked back.
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02-14-2013, 04:59 PM	#16
MrDummy →сяuisiиg iи му вмш← 73 Rep 1,642 Posts Drives: 2010 Space Gray 328i Join Date: May 2009 Location: The Unemployment Capitol of America iTrader: (1) Garage List 2010 BMW 328i [0.00]	I want to switch but I only have stock 16" tires so its not worth it IMO. Until I figure out what rims to get to replace current ones. I don't know how big I can go? Would 18" RIMs be the largest I should go with? __________________ SuPerMoD @ MassMonsterz.com A "Happy" Owner of a Metallic Space Gray 2010 BMW 328i ProGaMeR on the XboX 360
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02-14-2013, 06:16 PM	#18
j2m Colonel 187 Rep 2,446 Posts Drives: '11 E92 M3 DCT Join Date: Jun 2011 Location: Calgary, Ab iTrader: (8) Garage List 2011 BMW E92 M3 [10.00]	Your dealer is full of SHIT! tell them I said so __________________ 11' E92 M3 Space Grey \| DCT \| ESS VT2- 625 \| Gintani Race (valved) + Quad Res Catless X-Pipe \| KW Sleeve's \| GC Camber Plates\|Arkym Diffuser \| Vorsteiner VRS Lip \| P3 Boost Guage \| Stud Conversion PHOTO's: Click Here ESS VT2 625 PHOTOS: Click Here
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02-14-2013, 07:27 PM	#19
tunachris First Lieutenant 17 Rep 363 Posts Drives: 2010 E92 Join Date: Oct 2010 Location: Azusa, CA iTrader: (0) Garage List 2010 E92 [0.00]	Best move I ever made was switching to Michelin Pilot Super Sport non run-flats. Only problem is I go through tires at a horrendous rate. I get about 25,000 on the fronts, and at best maybe 12-13K on the rears. __________________ JB4, BMW Perf. Exhaust, DCI, Strut Brace, KW Series 1, Quaife LSD, Black Kidneys.
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02-14-2013, 07:42 PM	#20
AWil335i Second Lieutenant 12 Rep 281 Posts Drives: 2007 E92 335i Join Date: Oct 2012 Location: Indianapolis iTrader: (0) Garage List 2007 BMW E92 335i [0.00]	The PS2 RFTs aren't bad, but I just switched to Pilot Super Sports and they definitely have more grip. __________________ 07 E92 335I \| JB4 G5 ISO \| BMS E85 Flash \| DCI \| BMS DPs \| Helix FMIC \| Alpina TCU Flash \| Walbro GLS392 \| E70 \| 429rwhp/474rwtq \|
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02-15-2013, 12:10 AM	#22
driverman Captain 40 Rep 715 Posts Drives: 2008 328i 6MT - SOLD Join Date: Nov 2008 Location: El Dorado Hills, CA iTrader: (0)	This statement from the OP is true: "the whole handling dynamics of the car was designed based on runflats". It's also true that the M3 doesn't use RFT's. So how would our sport suspensions be different if BMW designed them for non RFT's? Does anyone know? I've read BMW used softer bushings to make up for the stiff sidewalls. After running original OEM Bridgestone RFT's then PS2's then DW's, I can tell you they all feel quite different. I can also tell you that DW's are 30 pounds lighter (as a set) than RFT's. Captain Audio posted good stuff on slip angles that explains why RFT's don't handle better even though they have better steering response.
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