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Discussion Starter #1
Michelin has released the Michelin PS2 "Zero Pressure"

and

Continental has released the Sport Contact 2 SSR

both are run flat versions of their top tires, and both have had their normal versions on the M5



Think they will put the new ones on the M5 ??
 

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Discussion Starter #3
mhh said:
From all I've read about the ride of run-flats, I hope not.
1st Generation Run flat on 5 Series are apparently not so great

but

2nd generation Run flats on 1 Series and new 3 Series are apparently very good
 

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SuperBMW said:
Michelin has released the Michelin PS2 "Zero Pressure"

and

Continental has released the Sport Contact 2 SSR

both are run flat versions of their top tires, and both have had their normal versions on the M5



Think they will put the new ones on the M5 ??
Why would you want to ruin the handling of a car with runflats???
 

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SuperBMW said:
1st Generation Run flat on 5 Series are apparently not so great

but

2nd generation Run flats on 1 Series and new 3 Series are apparently very good
I made a lot of kilometers in E87 (over 5000 so far) and I can't say that these run flat are very good. But I have heard that in E90 run flats are much better.
 

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run flat technology is getting better and BMW seems to be adopting their suspensions for the slightly different ride they offer. Id be a little surprised to see runflats on the M5, but it does give an advantage. I remember the news stories that ran here on tv and in newspapers about the poor souls who got stranded when their fancy new $80,000 BMW M car had a flat. While I am not a big fan of run flats from the past, keep an open mind, they might get better.
 

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Jerry, it would seem that this would be the ideal use for ARS. It would be able to soften up the ride to cope with the somewhat harsh nature of the run flat, and stiffen up to provide handling when needed. Makes sense to me.

After a flat my wife had in our 530 this winter, on a day that it was balmy 15 degrees F with wind hitting 40mph+.. Any winter tires I get will be run flats, even for the M5.
 

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Run-flats inherently need a strong (thick) sidewalls. The extra unsprung weight and the reduced pliability from rubber vs. air would seem to always work to disadvantage.

Tom
 

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bernhtp said:
Run-flats inherently need a strong (thick) sidewalls. The extra unsprung weight and the reduced pliability from rubber vs. air would seem to always work to disadvantage.

Tom
Absolutely. The bottom line is you'll be giving up some performance to avoid the inconvenience of being stuck with a flat tire. I'll rather risk the inconvenience.
 

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bernhtp said:
Run-flats inherently need a strong (thick) sidewalls. The extra unsprung weight and the reduced pliability from rubber vs. air would seem to always work to disadvantage.

Tom
And also it is giving worse grip when cornering.
 

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I had runflats on my 545i sports.... I replaced them with regular tires. It helped the a little. I noticed that with runflats the car cornered better due to harder sidewall. But I would gladly trade in the handling for a little softer ride...
BMW needs to fix their suspensions for these runflats.....
Also, I don't want to replace a tire just because I get a flat????
I would not want them on my M5 (as well as no active steering, no ARS, no SMG).
 

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Just a few thoughts...

ARS... well, I am curious as to why they did not include that with the M5. I can only guess weight of the system, and maybe it does not react as fast as a conventional setup to very fast weight changes. I dont think it would help very much, although I think for ride quality on the straight ahead, where roll bars are not being activated, would improve a little.

On the performance disadvantage- If the complaint is added unsprung weight, if BMW continues the trend to offer heavier wheels than the aftermarket, then this can be offset with aftermarket wheels. I wonder why BMW uses the wheels it does, I am left to guess again that it has to do with resistance to the bumps in the road. Ive been driving M cars in and around NYC for nearly a decade and in that time I've never bent an OEM rim. Ive scraped one or two, but not bent. The thing I always find attractive about any BMW is that it is a vehicle that not only is fun to drive, but does add some measure of practicality. So I would be understanding of them using run flats on the M5. Id like to see them offer the option and for those who do not take the option I am sure they would give a warning sticker about flats. On the Z8, I kept the run flats on when I was driving her longer distances, sometimes near not so great areas. Now that my drives are shorter distances and nicer areas, I decided to increase the performance and ride with regular sports tires (Pilot Sports) and the difference was noticeable. However, my run flat experience is with tires designed for a 2000 vehicle- we are now talking about 5-6 years into the future. I am sure that sooner or later we will have run flat benefits without most of the detriments.
 

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M5_2010 said:
I had runflats on my 545i sports.... I replaced them with regular tires. It helped the a little. I noticed that with runflats the car cornered better due to harder sidewall. But I would gladly trade in the handling for a little softer ride...
What tires you fited? Remember that there are huge diferences between tires in the same dimension. Try Conti and Yokohama. You will se... :hihi:
 

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MEnthusiast said:
I am sure that sooner or later we will have run flat benefits without most of the detriments.
I am sure that runflats will continue to improve, but so will regular tires. It's unclear to me whether the gap will significantly narrow.

It reminds me of capacity/price curve projections of bubble memory in the 80s and the predictions of capturing large market share at the expense of hard drives. What they failed to predict was that hard drive technology was advancing even more rapidly and so bubble memory never really emerged from its economic disadvantage.

Tom
 

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But run flats provide a real benefit to both consumers (ease of use & lighter vehicles) and automakers (lower cost to put 4 tires, instead of 5) in a car. Also, what are the improvements in tires? Grip, ride, life of the tire. Those improvements will happen in run flats too. Convienence is king, IMHO.

Finally, there are some who believe you cannot compare cars to computers, though I disagree with that. I think any comparison will never be perfect, but that does not make it invalid.
 

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MEnthusiast said:
Just a few thoughts...

ARS... well, I am curious as to why they did not include that with the M5. I can only guess weight of the system, and maybe it does not react as fast as a conventional setup to very fast weight changes. I dont think it would help very much, although I think for ride quality on the straight ahead, where roll bars are not being activated, would improve a little.

On the performance disadvantage- If the complaint is added unsprung weight, if BMW continues the trend to offer heavier wheels than the aftermarket, then this can be offset with aftermarket wheels. I wonder why BMW uses the wheels it does, I am left to guess again that it has to do with resistance to the bumps in the road. Ive been driving M cars in and around NYC for nearly a decade and in that time I've never bent an OEM rim. Ive scraped one or two, but not bent. The thing I always find attractive about any BMW is that it is a vehicle that not only is fun to drive, but does add some measure of practicality. So I would be understanding of them using run flats on the M5. Id like to see them offer the option and for those who do not take the option I am sure they would give a warning sticker about flats. On the Z8, I kept the run flats on when I was driving her longer distances, sometimes near not so great areas. Now that my drives are shorter distances and nicer areas, I decided to increase the performance and ride with regular sports tires (Pilot Sports) and the difference was noticeable. However, my run flat experience is with tires designed for a 2000 vehicle- we are now talking about 5-6 years into the future. I am sure that sooner or later we will have run flat benefits without most of the detriments.
The wheel and tire weight that BMW offers on their standard cars just baffles me. My OEM 18" wheels and runflats weighed in at 62lbs front and 64lbs rear. My 19" BBS wheels and Goodyear F1 GS-D3 tires tip the scales at 48lbs front and 50lbs rear. That's a savings of 56lbs of unsprung, rotating weight using 1" larger wheels and tires. For a company that puts such a high emphasis on performance, I don't understand why they're overlooking such a basic element.

It does appear they've addressed the wheel weight issue on the M6 anyways. I have no idea what the M5 wheels weigh.
 
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