Welcome to Bimmerfest -- The #1 Online Community for BMW related information! Please enjoy the discussion forums below and share your experiences with the 200,000 current, new and past BMW owners. The forums are broken out by car model and into other special interest sections such as BMW European Delivery and a special forum to voice your questions to the many BMW dealers on the site to assist our members!

Please follow the links below to help get you started!

Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 5 Series > F10 / F11 (2011 - Current)

F10 / F11 (2011 - Current)
The new chapter in the highly successful story of the BMW 5 Series Sedan (F10) and wagon (F11)

Reply
 
Thread Tools Display Modes
  #26  
Old 07-13-2013, 04:14 PM
Mark K's Avatar
Mark K Mark K is online now
Officially Welcomed to the 'Fest
Location: Cincinnati, OH
 
Join Date: Jun 2010
Posts: 1,991
Mein Auto: 2011 E92 335i MT
Quote:
Originally Posted by The X Men View Post
My take away was that the editors were surprise at how well the latest generation of runflat performs and the disadvantage of runflats are minimized in the latest generation of runflats. The mere mention of the possibility of a runflat tires out performing a convention tire, even if it was an older design, means that the lastest gen of runflat have vastly improved.
OK, X, I just finished reading this month's Roundel and somebody mentioned, almost in passing, that the possible FIRST candidate for RFT experiment in M stable will be M4. Actually, it was Satch Carlson on the last page saying that. I do not need to tell you that

- if no M car yet has run flats, there's a good reason for that

- even IF (a BIG if) run flats they (hypothetically) mount on a M4 can match "performance" of the similar non-run flat tire, that STILL doesn't mean that:

a) it will match the performance of a normal tire as far as mere humans (read: 99.9% of BMW's customers) are concerned. Numbers mean truly nothing in this case.

b) it will mean ANYTHING here, in this market (NA continent). All other problems still remain, we didn't become Germany overnight just because Bridgestone might have released a proper tire that can run when flat. What problems? Geography, availability, price, US roads ... and so on. Search.

So, no, as far as THIS market is concerned, there's not room nor need to mount run flat tires on cars by default. Mind bold. I simply mean that BMW is totally free (and I'm even willing to pay extra for it) to offer the OPTION of having run flat tires on their cars, but making that choice as default for North American customer is grossly asinine move. That's all.

OK, not really all. For as much as we whine and b|tch here on this forum about how driving is in Germany and as much as we might want to send our Congresspeople to mandatory "fact finding trip" to Germany where they have to drive rented car for at least a week ... we forget how desperately BMW engineers need to come out of the mom's (BMW's) basement and do a fact-finding trip to US. A trip coast-to-coast in a BMW with purposefully created flat in the middle of Alabama would be eye-opening. I bet you next gen vehicle would have space for a spare engineered in the trunk.
__________________

_____________________________________________

2011 E92 335i 6MT ZSP ZCW (ED May 17th 2010)

2013 118d BMWNA Special Edition. Black on black cloth (yay!), 5 door hatchback, 140hp diesel. Special edition items: factory debadge| "VW", "Golf" and "TDI" badges factory applied | MT | Standard go flat tires | Spare tire (yay!) | No moonroof (yay!) .
Reply With Quote
  #27  
Old 07-13-2013, 08:25 PM
wesleyan92 wesleyan92 is offline
Officially Welcomed to the 'Fest
Location: Allen TX
 
Join Date: Mar 2008
Posts: 469
Mein Auto: 2014 535i
My runflats are almost worn out; I am getting the new Michelin Pilot A/S 3. Absolutely no concerns about not carrying a spare - that is what roadside assistance is for
__________________
Current: 2012 535|| Titanium Silver, Black interior, M-sport, Premium, SAT, Nav, Apps

Retired: 2010 535|| White, Natural Brown interior, Sports, SAT, iPOD, Rear airbags

Retired - 2008 528 - Premium, iPod, Cold Weather, Titanium with black interior

Reply With Quote
  #28  
Old 07-13-2013, 10:06 PM
DavidNJ DavidNJ is offline
Just Confused...
Location: Warren, NJ
 
Join Date: Apr 2004
Posts: 310
Mein Auto: 01 530i; 04 S2k; 94 Supra
First, Wesleyan, that sounds like a good choice. It seems the Ultra High Performance Summer Tire segment has been abandoned. The AS3 is a brand new 2013 tire. Why did you chose it over the Pilot Super Sport? Its 500 wear rating vs. the PSS's 300? Or more flexibility in the occasional Texas cold wave?

I would carry an inflation kit with sealant. Even a loose compact spare and tools in a bag for longer trips.

Quote:
Originally Posted by The X Men View Post


Didn't you read my post before you respond to it, post #17:

"Tirerack did some testing of summer runflat tires and found them to perform as well if not better than their non-runflat counterparts:

"All four of the tires in our test proved you don't have to give up performance to get a run-flat's extended mobility. The Pilot Sport PS2 ZP really came alive when driven at the limit, displaying very responsive steering, excellent braking traction and stable cornering. It almost felt a little more composed and capable than we remember of the non-ZP version tested a few years ago."

http://www.tirerack.com/tires/tests/...y.jsp?ttid=158 "

You don't like runflats, can we both agree on that? All I am saying is that runflat perform good enough for 90% of the BMW owners out there who do not track their cars. I hated my runflats on my 08 GS350, but the lastest gen of runflats on my F10 is not too bad. I bought the F10 thinking I would hate the runflats and I would change them out as soon as they wear out, but a year and half later, I am thinking my next set of tires will be runflats as well.
First, that was a 2011 test of a 2008 runflat version of a 2004 regular tire. And it isn't available in F10 sizes.

Your link was broken. This is the review: http://www.tirerack.com/tires/tests/...y.jsp?ttid=158. This is a review of the regular versions: http://www.tirerack.com/tires/tests/....jsp?ttid=140/ And this is the review of current tires (some already replaced): http://www.tirerack.com/tires/tests/...y.jsp?ttid=148. This is the 2012 test done with Car and Driver and Tire Rack; the Michelin PSS was a runaway winner.

For an F10, the options are RE50A, ContiSportContact 3, P-Zero, and SP Sport Maxx GT. I don't think anyone in their right mind (pretty much everyone on this forum seems to be in their right mind) would get the non-runflat version of any of these tires unless it was the only one in their size.

It seems clear to me Wesleyan92 has the right idea. Depending on the person, the PSAS3 or PSS/PA4 summer/winter combo would probably be the right solution. The original tires could be saved for lease turn in. Tire/wheel insurance wouldn't be as critical. The difference in cost would be enough to pay for a space saver spare with tools.

Note: I didn't have this view when I started the thread.

Last edited by DavidNJ; 07-13-2013 at 10:12 PM.
Reply With Quote
  #29  
Old 07-14-2013, 07:01 AM
The X Men The X Men is online now
Officially Welcomed to the 'Fest
Location: MA
 
Join Date: Mar 2012
Posts: 4,716
Mein Auto: 2012 535xi 2013 X3 35i
Quote:
Originally Posted by DavidNJ View Post
First, that was a 2011 test of a 2008 runflat version of a 2004 regular tire. And it isn't available in F10 sizes.
Your link was broken. This is the review: http://www.tirerack.com/tires/tests/...y.jsp?ttid=158. This is a review of the regular versions: http://www.tirerack.com/tires/tests/....jsp?ttid=140/ And this is the review of current tires (some already replaced): http://www.tirerack.com/tires/tests/...y.jsp?ttid=148. This is the 2012 test done with Car and Driver and Tire Rack; the Michelin PSS was a runaway winner.
For an F10, the options are RE50A, ContiSportContact 3, P-Zero, and SP Sport Maxx GT. I don't think anyone in their right mind (pretty much everyone on this forum seems to be in their right mind) would get the non-runflat version of any of these tires unless it was the only one in their size.
It seems clear to me Wesleyan92 has the right idea. Depending on the person, the PSAS3 or PSS/PA4 summer/winter combo would probably be the right solution. The original tires could be saved for lease turn in. Tire/wheel insurance wouldn't be as critical. The difference in cost would be enough to pay for a space saver spare with tools.
Note: I didn't have this view when I started the thread.
You are still missing my point, my point was given two tires of the same brand and model, one runflat and one conventional, the performance difference is not that much. If someone like you who like to push their car to the limit, then the available runflat tires for the F10 may not satisfy your needs, therefore you have to go with conventional tires. For the majority of the F10 drivers out there, they are fine with the runflat tires. If you are going to start comparing differently type of tires, then your thread title should read, How much did Michelin pilot sport or whatever tires help with your handling.
Reply With Quote
  #30  
Old 07-14-2013, 07:09 AM
The X Men The X Men is online now
Officially Welcomed to the 'Fest
Location: MA
 
Join Date: Mar 2012
Posts: 4,716
Mein Auto: 2012 535xi 2013 X3 35i
Quote:
Originally Posted by Mark K View Post
So, no, as far as THIS market is concerned, there's not room nor need to mount run flat tires on cars by default. Mind bold. I simply mean that BMW is totally free (and I'm even willing to pay extra for it) to offer the OPTION of having run flat tires on their cars, but making that choice as default for North American customer is grossly asinine move. That's all.
I certainly agree with that, runflats should be an option, not standard. Even with runflats, there should be an option to buy a oem spare tire and BMW should also design the space needed in the trunk to store a spare.
Reply With Quote
  #31  
Old 07-14-2013, 08:25 AM
wesleyan92 wesleyan92 is offline
Officially Welcomed to the 'Fest
Location: Allen TX
 
Join Date: Mar 2008
Posts: 469
Mein Auto: 2014 535i
Quote:
Originally Posted by DavidNJ View Post
First, Wesleyan, that sounds like a good choice. It seems the Ultra High Performance Summer Tire segment has been abandoned. The AS3 is a brand new 2013 tire. Why did you chose it over the Pilot Super Sport? Its 500 wear rating vs. the PSS's 300? Or more flexibility in the occasional Texas cold wave?

I would carry an inflation kit with sealant. Even a loose compact spare and tools in a bag for longer trips.
Thanks David; I think I went with the A/S3 because it is what Discount Tire recommended. Plus will be good to have during those rare Dallas winter days. I have never gone with a pure summer performance tire. What would you recommend?
__________________
Current: 2012 535|| Titanium Silver, Black interior, M-sport, Premium, SAT, Nav, Apps

Retired: 2010 535|| White, Natural Brown interior, Sports, SAT, iPOD, Rear airbags

Retired - 2008 528 - Premium, iPod, Cold Weather, Titanium with black interior

Reply With Quote
  #32  
Old 07-14-2013, 09:45 AM
dunderhi's Avatar
dunderhi dunderhi is online now
0-60 in 4 secs or less!
Location: MD
 
Join Date: Dec 2006
Posts: 5,745
Mein Auto: '13 X5M, 650xi
Quote:
Originally Posted by The X Men View Post
You are still missing my point, my point was given two tires of the same brand and model, one runflat and one conventional, the performance difference is not that much. If someone like you who like to push their car to the limit, then the available runflat tires for the F10 may not satisfy your needs, therefore you have to go with conventional tires. For the majority of the F10 drivers out there, they are fine with the runflat tires. If you are going to start comparing differently type of tires, then your thread title should read, How much did Michelin pilot sport or whatever tires help with your handling.
First let me disclose my bias: I am a frequent TireRack customer, as such I realize that TireRack is in the business of selling me tires. It seems to me that any recommendation that they make from their testing seems to gravitate towards suggesting that the consumer spend more money. They compare great performing snow tires to poor performing all-seasons and conclude that everyone needs to by a winter set of tires. I called TireRack for snow tires for the X5M and they didn't have any snow tires for the X5M, but all of the sudden the A/S Conti DWS, which they did have is stock, is great in the snow (which I already knew) despite every test on their site concluding A/S tires are ineffective in the snow. Thus, I trust Car & Driver and Automobile tire tests more than someone with a vested interest in selling me tires.


So here's my analysis. Take any theoretical pair of tires; both the same model, but one RFT and one that is not. What will be the differences?

1) Dry Performance - nearly identical
2) Wet Performance - nearly identical
3) Slalom - nearly identical
4) Lap Time - nearly identical
5) Stopping Distance - nearly identical
6) Average Cornering Force - nearly identical

So why buy a nonRFT?
7) Fuel consumption - nonRFT advantage
8) Ride Comfort - nonRFT advantage
9) Feedback near the limit - nonRFT advantage
10) Model Availability (ie Mich PSS) -nonRFT advantage
11) Tire Shop Availability - nonRFT advantage
12 ) Tire Price - nonRFT advantage


So why buy an RFT?
13) Drive while flat - RFT advantage
14) High Speed blowout - RFT advantage
__________________


2013 X5M ........ 2013 650xi ...... 2011 550xi (ret) 2011 335d (ret)

Last edited by dunderhi; 07-14-2013 at 10:45 AM. Reason: Modified with contributions
Reply With Quote
  #33  
Old 07-14-2013, 10:10 AM
Mark K's Avatar
Mark K Mark K is online now
Officially Welcomed to the 'Fest
Location: Cincinnati, OH
 
Join Date: Jun 2010
Posts: 1,991
Mein Auto: 2011 E92 335i MT
Quote:
Originally Posted by dunderhi View Post
So why buy a nonRFT?
7) Fuel consumption - nonRFT advantage
8) Ride Comfort - nonRFT advantage
9) Feedback near the limit - nonRFT advantage
10) Model Availability (ie Mich PSS) -nonRFT advantage
11) Tire Shop Availability - nonRFT advantage


So why buy an RFT?
12) Drive while flat - RFT advantage
I know that it probably doesn't matter to YOU, but I would insert

7a) Tire Price - nonRFT advantage

__________________

_____________________________________________

2011 E92 335i 6MT ZSP ZCW (ED May 17th 2010)

2013 118d BMWNA Special Edition. Black on black cloth (yay!), 5 door hatchback, 140hp diesel. Special edition items: factory debadge| "VW", "Golf" and "TDI" badges factory applied | MT | Standard go flat tires | Spare tire (yay!) | No moonroof (yay!) .
Reply With Quote
  #34  
Old 07-14-2013, 10:32 AM
The X Men The X Men is online now
Officially Welcomed to the 'Fest
Location: MA
 
Join Date: Mar 2012
Posts: 4,716
Mein Auto: 2012 535xi 2013 X3 35i
Quote:
Originally Posted by Mark K View Post
I know that it probably doesn't matter to YOU, but I would insert

7a) Tire Price - nonRFT advantage

I also like to add an advantage for runflats:

2) Safety - Runflat tires can save your life in the event of a high speed blow out.
Reply With Quote
  #35  
Old 07-14-2013, 10:43 AM
DavidNJ DavidNJ is offline
Just Confused...
Location: Warren, NJ
 
Join Date: Apr 2004
Posts: 310
Mein Auto: 01 530i; 04 S2k; 94 Supra
Wesleyan, in my last post there was a link to a 2012 C&D tire test, the Michelin Pilot Super Sport was the runaway winner. If you search "Super Sport" here or in google, you will have owners raving about them. Rated by Tire Rack as a Max Performance Tire with a wear rating of 300, it caused lots of people chose that tire over the Extreme performance/wear rating under 200 Dunlop Z1 Star Spec and Bridgestone RE11. You can see that the various sports car forums such has the ones for the S2000.

dunderhi, if you read the various posts here people report an improvement in all aspects of handling except steering response. Comparing the same brand and model tire isn't really valid either; the best tires don't come as runflats. The newest tire a runflat is based off are the all-season ultra high performance RE960AS and PS AS Plus, both a model behind and at least 5 years old and both rarely mentioned here. One reason, the PS AS Plus ZP doesn't come in F10 sizes.

X Men, other than what was mentioned above, you have only one back-to-back test, Tire Rack's test of RFT and regular versions of the RE960AS: Tire Rack - Is the Third Generation Bridgestone Potenza RE960AS Pole Position RFT 3G Run-Flat the Charm?

However, that is the newest runflat design, not equal to the newest non-runflat design, and a runflat that is not OEM nor used by many on this forum. It is, based on my third hand research, the only run flat recommendation I would make. Owners say:

Quote:
"Night and Day difference in ride quality between stock potenzas and my last set of pilot sport SP2 ZP's. Although these are not as sticky as the SP2's, they hold thier own on this moderately powered 06' 330i Sport Pkg. Really very impressed with this tire so far. If you are looking for a good all around performer with great comfort and run flat - you just found your tire."
Quote:
"The Potenza RE960AS Pole Position RFT replaced OEM Potenza previous generation summer tires on my 2007 BMW 328i with sport package. I was considering Michelin Pilot Sport go-flat tires, but I do like the run flat concept. These tires give a softer, smoother, quieter ride than the originals. They work well on wet pavement and seem to corner about as well as the OEM tires."
Quote:
"my 2011 335d w/sports pkg shipped with Michelin Pilot Sport PS2 ZP rft summer tires, an amazing tire (my favorite rft for summer) but harsh on the ride quality in terms of impact when hitting bumps and such. it was time for new tires and i wanted an all-season tire that i could use in cold conditions (35F-60F), rain, and possibly light snow. i also needed an rft tire as my car does not have room for a spare. i got very frustrated in my search and was close to just buying non-rft tires, Continental ExtremeContact DWS to be exact, because i couldn't find any high performance all-season rfts that had a softer ride and positive reviews. the only tire i could find were the Bridgestone Potenza RE050A RFT, which i read had harsh ride quality and they were not all-season.

i hesitantly ordered these Bridgestone Potenza RE960AS Pole Position RFT tires hoping that i would not have wasted $1200. they were very new and i couldn't find any specific reviews concerning these tires on an E90 335d. boy was i pleasantly surprised when i drove away with these tires. they honestly feel/act like non-rft tires!! the ride is just perfect, not too soft, not too harsh. with the Michelin Pilot Sport PS2 ZP, every time i hit a bump, i clenched my teeth and my body would tense up because of the impact on my car...i felt like every bump was damaging my rims or suspension...i hated it.

i have driven in rain and cold ( 34F-104F wet and dry) at both city and highway speeds, and these tires have done great. i don't feel like i have compromised the awesome performance characteristics of my car, yet i get a little bit softer rft ride quality. honestly, these tires don't ride like other rfts. again, they ride like non-rft tires. i gotta hand it to Bridgestone***133;.fantastic engineering with these tires. the only thing i have not done is drive in snow with the new tires, and i'm not sure i feel safe doing so with 425 lb of torque at the rear wheels. i highly recommend."
Net, if you get the RE960AS you are someplace in the range of an ok high performance all-season RFT. Not the best, but ok. You have still spent 38% more than the non-RFT RE970AS. 970? Yes, the RE960 is so old it isn't available in F10 sizes anymore!
Reply With Quote
  #36  
Old 07-14-2013, 10:53 AM
dunderhi's Avatar
dunderhi dunderhi is online now
0-60 in 4 secs or less!
Location: MD
 
Join Date: Dec 2006
Posts: 5,745
Mein Auto: '13 X5M, 650xi
Quote:
Originally Posted by Mark K View Post
I know that it probably doesn't matter to YOU, but I would insert

7a) Tire Price - nonRFT advantage

Added, but in my defense my tire purchase usually includes new wheels, so the tire portion of the bill is smaller.

Quote:
Originally Posted by The X Men View Post
I also like to add an advantage for runflats:

2) Safety - Runflat tires can save your life in the event of a high speed blow out.
Added
__________________


2013 X5M ........ 2013 650xi ...... 2011 550xi (ret) 2011 335d (ret)
Reply With Quote
  #37  
Old 07-14-2013, 11:08 AM
DavidNJ DavidNJ is offline
Just Confused...
Location: Warren, NJ
 
Join Date: Apr 2004
Posts: 310
Mein Auto: 01 530i; 04 S2k; 94 Supra
This comment deserves its own post. Everyone posting is pretty much a 535/550 person...or 535d However, dealers sell most 528s and the story there isn't good.

In the standard 17" 225/55-17 there are few options. The RE960AS RFT is available. AS is the ContiExtremeContact DWS in non-runflat. Good news is there are two good runflat winter tire options: Dunlop's Winter Sport 3D DSST and Bridgestone's LM-32 RFT.

For a M-Sport/Luxury/Modern with 245/45-18s the selection is the same as the for the 535/550. For the M-Sport though, the selection is limited again; the wide rear in 18" is simply not available. M-Sport choices for none RFT are all season ContiExtremeContact DWS and the new Pilot Sport AS3. In runflat, just the antique BMW OEM offerings. It does have one split winter offering: the Pirelli Winter Sottozero Serie II Run Flat.
Reply With Quote
  #38  
Old 07-14-2013, 11:42 AM
MoldCAD's Avatar
MoldCAD MoldCAD is online now
Officially Welcomed to the 'Fest
Location: Poland
 
Join Date: Jan 2013
Posts: 993
Send a message via Skype™ to MoldCAD
Mein Auto: 528i xDrive
Perhaps not offered in the US, but the staggered 18" setup with ContiSportContact 3 setup with 350 M wheels is what I have on 528xi (245/45 front, 275/40 rear). For winter I'm using a square set (Dunlops on the OEM 328 wheels).
__________________
previous: 2003 E46 330i SMG
current: 2013 F10 528i xDrive
on order: Golf R mk7 DSG

Reply With Quote
  #39  
Old 07-14-2013, 05:51 PM
dunderhi's Avatar
dunderhi dunderhi is online now
0-60 in 4 secs or less!
Location: MD
 
Join Date: Dec 2006
Posts: 5,745
Mein Auto: '13 X5M, 650xi
Quote:
Originally Posted by DavidNJ View Post
dunderhi, if you read the various posts here people report an improvement in all aspects of handling except steering response. Comparing the same brand and model tire isn't really valid either; the best tires don't come as runflats. The newest tire a runflat is based off are the all-season ultra high performance RE960AS and PS AS Plus, both a model behind and at least 5 years old and both rarely mentioned here. One reason, the PS AS Plus ZP doesn't come in F10 sizes.
I believe my observations hold true if the only difference was the runflat sidewall reinforcement. Many off us who have raved about the improvements when we switch to nonRFTs are switching to much higher quality tires. Going from a crappy Goodyear Eagle LS Grand Touring A/S RFT to a Max Performance Michelin PSS Summer nonRFT will earn praise in every category including steering response. Going from a GY Eagle LS to a high performance A/S like the Conti DWS will earn praise in most categories. Going from a GY Eagle LS to a GY Assurance Grand Touring tire would probably yield little praise. Most likely the difference is improved ride at the expense of steering crispness. Thus, IMHO the praise is is not solely due to the tire's sidewall construction, but in the tire itself. So, why isn't there a Michelin PSS RFT? I would assume market demand rather than any technological challenge are holding RFTs back. If BMW decided to put RFTs on their M cars, I bet there would be a PSS RFT.
__________________


2013 X5M ........ 2013 650xi ...... 2011 550xi (ret) 2011 335d (ret)
Reply With Quote
  #40  
Old 07-14-2013, 09:20 PM
DavidNJ DavidNJ is offline
Just Confused...
Location: Warren, NJ
 
Join Date: Apr 2004
Posts: 310
Mein Auto: 01 530i; 04 S2k; 94 Supra
Quote:
Originally Posted by dunderhi View Post
I believe my observations hold true if the only difference was the runflat sidewall reinforcement. Many off us who have raved about the improvements when we switch to nonRFTs are switching to much higher quality tires. Going from a crappy Goodyear Eagle LS Grand Touring A/S RFT to a Max Performance Michelin PSS Summer nonRFT will earn praise in every category including steering response. Going from a GY Eagle LS to a high performance A/S like the Conti DWS will earn praise in most categories. Going from a GY Eagle LS to a GY Assurance Grand Touring tire would probably yield little praise. Most likely the difference is improved ride at the expense of steering crispness. Thus, IMHO the praise is is not solely due to the tire's sidewall construction, but in the tire itself. So, why isn't there a Michelin PSS RFT? I would assume market demand rather than any technological challenge are holding RFTs back. If BMW decided to put RFTs on their M cars, I bet there would be a PSS RFT.
Actually, it is a bit more than that. The tire is effectively a spring and damper in series with the suspension's spring and damper. Stable handling is when the combination maintains an even load on the tire as it goes over road irregularities allowing it to maintain a consistent if not constant slip angle. If the tire loads and unload the slip angle is constantly changing and the driver is sawing at the wheel.

The stiff sidewalls make that harder. If it was just a transparent reinforcement every tire would be offered as a runflat. There is one back to back test where the two are similar, the Tire Rack test of the RE960AS, a 2011 tire. However, it was already a generation old when introduced.

The story may be a bit better for 3-series where some other newer tires, Bridgestone S001 and Michelin Pilot Sport Plus ZP all seasons, are available. They don't have sizes for the F10.

The claim was that they offer more stability in a high speed blowout. I've only seen two posts of people who had those blowouts, on on an 3-series, one on a Corvette. I'm not sure how big the difference is. Or if the probability of the failure is the same for both tires.

When BMW went to runflats, spares were common. Now that they aren't we can see what other manufacturers have done. The Corvette and Viper used runflats. Porsche and BMW M-series use inflators and sealant. MB has a couple of runflat models, the 2014 Infiniti Q50 also appears to have runflats, it will be interesting to see which ones. But the net is an inflator (compressor or can) and sealant seem to be a viable alternative.

This is what can happen without a spare: http://forums.rennlist.com/rennforum...tory-long.html Not a friendly story...over 22 hours. If he had a spare he would have been on his way. If he had runflats, would he have gotten home??? It was a sidewall failure 2 hours from the nearest dealer. He has a list of recommendations:

Quote:
Things you need when traveling remotely:

1) All contact info for nearby Porsche Dealers.

2) Some sort of flatbed subscription like RA, AAA, etc. - the driver told me my service would have been $800 if I'd have had to pay it!

3) Wheel and tire warranty...in my spare tire story I'll tell you about the nail in the front tire I found while testing out the spare...another new tire coming to me soon...

4) WATER WATER WATER - and snacks would be good, and maybe BEER too

5) Pre-arrangements with possible high performance car tire shops in the areas of travel if Porsche service density is low.

6) Flashlight, pen, paper, good cellphone charge.

7) Tire repair Kit - sure, go ahead and tell yourself that's gonna help...

Oh, and Duh!!! 8) a @#*$%@! Spare Tire!!!!

Last edited by DavidNJ; 07-14-2013 at 09:32 PM.
Reply With Quote
  #41  
Old 07-14-2013, 10:47 PM
dunderhi's Avatar
dunderhi dunderhi is online now
0-60 in 4 secs or less!
Location: MD
 
Join Date: Dec 2006
Posts: 5,745
Mein Auto: '13 X5M, 650xi
Quote:
Originally Posted by DavidNJ View Post
Actually, it is a bit more than that. The tire is effectively a spring and damper in series with the suspension's spring and damper. Stable handling is when the combination maintains an even load on the tire as it goes over road irregularities allowing it to maintain a consistent if not constant slip angle. If the tire loads and unload the slip angle is constantly changing and the driver is sawing at the wheel.

The stiff sidewalls make that harder. If it was just a transparent reinforcement every tire would be offered as a runflat. There is one back to back test where the two are similar, the Tire Rack test of the RE960AS, a 2011 tire. However, it was already a generation old when introduced.

The story may be a bit better for 3-series where some other newer tires, Bridgestone S001 and Michelin Pilot Sport Plus ZP all seasons, are available. They don't have sizes for the F10.

The claim was that they offer more stability in a high speed blowout. I've only seen two posts of people who had those blowouts, on on an 3-series, one on a Corvette. I'm not sure how big the difference is. Or if the probability of the failure is the same for both tires.

When BMW went to runflats, spares were common. Now that they aren't we can see what other manufacturers have done. The Corvette and Viper used runflats. Porsche and BMW M-series use inflators and sealant. MB has a couple of runflat models, the 2014 Infiniti Q50 also appears to have runflats, it will be interesting to see which ones. But the net is an inflator (compressor or can) and sealant seem to be a viable alternative.

This is what can happen without a spare: http://forums.rennlist.com/rennforum...tory-long.html Not a friendly story...over 22 hours. If he had a spare he would have been on his way. If he had runflats, would he have gotten home??? It was a sidewall failure 2 hours from the nearest dealer. He has a list of recommendations:
Don't forget you actually have an actual spring in your spring and damper system. The F10 has soft springs designed for the additional stiffness and weight of the RFT. There is no issue as designed. The softer nonRFT tires actually introduce change in the F10 suspension system as it was designed. Needsdecaf found that the soft Conti DWS was terrible for his car. Any tire test that would be truly an apples to apples test would have the proper suspension tuning for each type of tire. TireRack does not do this type of suspension tuning.

Anyway since we do not drive on perfectly smooth racetracks all of the time, RFT's do create a challenge for suspension engineers since soft springs contribute to additional body roll. BMW's solution is ARS. If BMW wants to minimize role without ARS, they will put stiff springs on a car like they did for my 335d Sport. Stiff springs and RFTs can lead to a harsh ride over pavement irregulaties, since something is needed to provide a reasonable amount of cushion.

So this is where unsprung weight becomes important and why I switch out wheels and tires. The nonRFT introduces softness into the suspension system, where the tire now absorbs the lion's share of the impacts due to a heavy wheel which was design to survive RFT impacts. Now if the wheel is lighter, the effect is to transfer more of the impact back into the springs where it was designed to be absorbed. With lighter wheels and softer tires, I found the springs in my 550i were too soft and needed to be replaced, but in my 650 the stiffer OEM springs are working great. As a lay person, some experimentation is required. Changing the type of tire may only produce a part of a desired solution, while on the otherhand it may introduce negative effects in the oeverall handling.

As far as the poor rennlist guy, he may have had some more options:
1) Call a cab or a rental car company
2) Drive on the shoulder at a low speed until he gets to a safe place. Since he had a tire that couldn't hold a plug it was toast anyway. One might do some rim damage, but the same is true if driving 55mph on a deflated RFT.
3) Call his insurance company or AAA if he has that option


Given all of these tire horror stories that surface during these debates, someone tell how this poor Porsche drivers outcome would have been different if he had RFTs, but his engine died instead. He still would have been stranded, right?
__________________


2013 X5M ........ 2013 650xi ...... 2011 550xi (ret) 2011 335d (ret)
Reply With Quote
  #42  
Old 07-15-2013, 02:20 AM
DavidNJ DavidNJ is offline
Just Confused...
Location: Warren, NJ
 
Join Date: Apr 2004
Posts: 310
Mein Auto: 01 530i; 04 S2k; 94 Supra
Quote:
Originally Posted by dunderhi View Post
Don't forget you actually have an actual spring in your spring and damper system. The F10 has soft springs designed for the additional stiffness and weight of the RFT. There is no issue as designed. The softer nonRFT tires actually introduce change in the F10 suspension system as it was designed. Needsdecaf found that the soft Conti DWS was terrible for his car. Any tire test that would be truly an apples to apples test would have the proper suspension tuning for each type of tire. TireRack does not do this type of suspension tuning.

Anyway since we do not drive on perfectly smooth racetracks all of the time, RFT's do create a challenge for suspension engineers since soft springs contribute to additional body roll. BMW's solution is ARS. If BMW wants to minimize role without ARS, they will put stiff springs on a car like they did for my 335d Sport. Stiff springs and RFTs can lead to a harsh ride over pavement irregulaties, since something is needed to provide a reasonable amount of cushion.

So this is where unsprung weight becomes important and why I switch out wheels and tires. The nonRFT introduces softness into the suspension system, where the tire now absorbs the lion's share of the impacts due to a heavy wheel which was design to survive RFT impacts. Now if the wheel is lighter, the effect is to transfer more of the impact back into the springs where it was designed to be absorbed. With lighter wheels and softer tires, I found the springs in my 550i were too soft and needed to be replaced, but in my 650 the stiffer OEM springs are working great. As a lay person, some experimentation is required. Changing the type of tire may only produce a part of a desired solution, while on the otherhand it may introduce negative effects in the oeverall handling.

As far as the poor rennlist guy, he may have had some more options:
1) Call a cab or a rental car company
2) Drive on the shoulder at a low speed until he gets to a safe place. Since he had a tire that couldn't hold a plug it was toast anyway. One might do some rim damage, but the same is true if driving 55mph on a deflated RFT.
3) Call his insurance company or AAA if he has that option


Given all of these tire horror stories that surface during these debates, someone tell how this poor Porsche drivers outcome would have been different if he had RFTs, but his engine died instead. He still would have been stranded, right?
A few things.

1) The Porsche owner had the same dilemma some BMW owners on this forum had. He had insurance/warranty that paid for towing to the nearest Porsche dealer. This was complicated by repair shops not having the tire or willing to work on the car. Similar problem that BMW owners had. Having been towed to the dealer, he would have maybe a 4 hour round trip to go home and back. It was simply easier and less expensive to wait. Full size spares always avoided that problem.

2) You are right; there is a concern that the BMW suspension may be too soft with standard tires. One reason I asked the question here. Probably less so with max performance.

3) In a 4200# car, the difference in 10# wheel, if that (PSS 2=24#, ContiSportContact 3=32#) makes in unsprung weight is insignificant. It is also unlikely that any activity will be measured finely enough to detect the difference in rotational inertia. Note, that the entire hub, brakes, upright (or moving part of the the strut), half the spring, moving part of the shock, half the suspension, half the halfshafts are all unsprung weight. Off road vehicles, whose wheels have to follow the most undulating surfaces, don't have lightweight wheel/tire assemblies and work just fine.

While tires contribute to rotational inertia because of their radius, engine components under 100mph are typically turning 6x-12x faster. In stock car racing you have big Chevy journals (2.1" dia) and small journals (2.0"). However the trick setup became Honda Journals (1.88"). This took weight off the crank and the rods the maximum diameter of the crank. You could do this with 4130 rods and cranks. In stock car racing an extra foot or two down a short straight could mean the difference of making a pass or having to back off.

4) The damping plays a big role. The force from the spring is proportional to displacement, not a lot of it for small movement. The shock responds to the speed of the movement. That is why you have digressive and now regressive shocks and features like the Koni FSDs. http://www.penskeshocks.com/files/racecar.pdf. A typical stock car rides like a 1950s Caddy. Solid engine and transmission mounts and a rather loud exhaust under the cockpit kills that mood though.

5) I think ARS was a response to Active Body Control. At the time MB first introduced it, ABC was a new MB feature. It since has move to the 5-series. It affects the roll couple, which is probably not affected too much by the tire stiffness. Dynamic dampers, available on most (all?) BMW models are more likely the response to the stiff tires. MB barely makes them available on the E-class (optional only on the rare E550, not at all on the C-class).

6) Tire stiffness is significantly affected by tire pressure. How did you tune the tire pressure on your 550i and 650i after you changed to non-runflats? I'd probably recommend a tool like this that cuts a shallow groove across the thread. My guess is pressure could make the non-runflats pretty stiff. I remember in the 1970s we used to run SCCA showroom stock sedan tire pressures in the high 40s.

Reply With Quote
  #43  
Old 07-15-2013, 05:21 AM
dunderhi's Avatar
dunderhi dunderhi is online now
0-60 in 4 secs or less!
Location: MD
 
Join Date: Dec 2006
Posts: 5,745
Mein Auto: '13 X5M, 650xi
Quote:
Originally Posted by DavidNJ View Post
A few things.

1) The Porsche owner had the same dilemma some BMW owners on this forum had. He had insurance/warranty that paid for towing to the nearest Porsche dealer. This was complicated by repair shops not having the tire or willing to work on the car. Similar problem that BMW owners had. Having been towed to the dealer, he would have maybe a 4 hour round trip to go home and back. It was simply easier and less expensive to wait. Full size spares always avoided that problem.

2) You are right; there is a concern that the BMW suspension may be too soft with standard tires. One reason I asked the question here. Probably less so with max performance.

3) In a 4200# car, the difference in 10# wheel, if that (PSS 2=24#, ContiSportContact 3=32#) makes in unsprung weight is insignificant. It is also unlikely that any activity will be measured finely enough to detect the difference in rotational inertia. Note, that the entire hub, brakes, upright (or moving part of the the strut), half the spring, moving part of the shock, half the suspension, half the halfshafts are all unsprung weight. Off road vehicles, whose wheels have to follow the most undulating surfaces, don't have lightweight wheel/tire assemblies and work just fine.

While tires contribute to rotational inertia because of their radius, engine components under 100mph are typically turning 6x-12x faster. In stock car racing you have big Chevy journals (2.1" dia) and small journals (2.0"). However the trick setup became Honda Journals (1.88"). This took weight off the crank and the rods the maximum diameter of the crank. You could do this with 4130 rods and cranks. In stock car racing an extra foot or two down a short straight could mean the difference of making a pass or having to back off.

4) The damping plays a big role. The force from the spring is proportional to displacement, not a lot of it for small movement. The shock responds to the speed of the movement. That is why you have digressive and now regressive shocks and features like the Koni FSDs. http://www.penskeshocks.com/files/racecar.pdf. A typical stock car rides like a 1950s Caddy. Solid engine and transmission mounts and a rather loud exhaust under the cockpit kills that mood though.

5) I think ARS was a response to Active Body Control. At the time MB first introduced it, ABC was a new MB feature. It since has move to the 5-series. It affects the roll couple, which is probably not affected too much by the tire stiffness. Dynamic dampers, available on most (all?) BMW models are more likely the response to the stiff tires. MB barely makes them available on the E-class (optional only on the rare E550, not at all on the C-class).

6) Tire stiffness is significantly affected by tire pressure. How did you tune the tire pressure on your 550i and 650i after you changed to non-runflats? I'd probably recommend a tool like this that cuts a shallow groove across the thread. My guess is pressure could make the non-runflats pretty stiff. I remember in the 1970s we used to run SCCA showroom stock sedan tire pressures in the high 40s.

In my experience of owning both an F10 and an F13, reducing 71lbs of unsprung rotational weight is significant in the way these cars ride and handle. Dare I say a night & day difference, such as pushing the Understeer towards Neutral. As I have also stated, experimentation was required, so my nonRFTs worked best at 40psi on my F10 and 38psi on my F13 were my solution was to optimize the balance between ride and handling. Based upon my tire wear at 25-30kmi on my PSS, I set the pressure correctly. As we have discussed in another thread, I'm not a Mom & Pop style of driver, so I do spend time using and testing the performance capabilities of my cars. Anyway, you seem to know best without actually trying anything yourself, so have fun with your tires and whatever they do to your car's handling. With any luck, you might drive your car hard enough someday to notice a difference. Good luck.
__________________


2013 X5M ........ 2013 650xi ...... 2011 550xi (ret) 2011 335d (ret)

Last edited by dunderhi; 07-15-2013 at 07:45 AM. Reason: typo
Reply With Quote
  #44  
Old 07-15-2013, 06:28 AM
swajames swajames is offline
Officially Welcomed to the 'Fest
Location: Silicon Valley
 
Join Date: Jan 2005
Posts: 996
Mein Auto: Jaguar F-Type V8 S
DavidNJ, your point 3 is flat out wrong. A reduction in unsprung mass has an impact that is much greater than a commemsurate reduction in sprung mass.
__________________
2014 Jaguar F-Type V8 S
Range Rover HSE Lux, Orkney Gray, Sand interior
Porsche 911 Carrera S Convertible, Midnight Blue, 6-Speed
BMW 550i, BMW 545i
Reply With Quote
  #45  
Old 07-15-2013, 08:50 AM
demas's Avatar
demas demas is offline
Officially Welcomed to the 'Fest
Location: Tokyo
 
Join Date: Apr 2007
Posts: 1,093
Mein Auto: F10 550i M-Sport
Interesting thread and point about the tires as part of a holistic suspension setup.

My car came with Michelin Primacy HP RFT's (active drive w/style 351's). I planned to change to Michelin PSS early on but wanted to try out the stock setup for a while.

I don't track and this is my first set of RFT's but find them surprisingly adequate even when pushing 4000lb's on lock-to-lock twisty mountain roads as I did a week ago.

They far surpassed the ContiSport Contact 3's I had on my 540 from a dry grip level where I felt the Conti's way underperformed. I was running a DME tuned E39, M5 RSB and Bilstein HDs w/OEM Sport shocks. I think the Conti's just didn't match my setup. Staggered 18" style 32's with 2.4/2.6 bar - I won't go near Continentals again.

With the F10, reducing un-sprung weight with PSS is enticing but interesting that the springs are matched to RFT weight and sidewall stiffness. If that were indeed true, I may be a little hesitant to disturb that formula given my positive experience with the ride so far.


However, I was thinking to go with the PSS matched with RD springs sometime in the future.
__________________
Reply With Quote
  #46  
Old 07-15-2013, 11:48 AM
DavidNJ DavidNJ is offline
Just Confused...
Location: Warren, NJ
 
Join Date: Apr 2004
Posts: 310
Mein Auto: 01 530i; 04 S2k; 94 Supra
Quote:
Originally Posted by swajames View Post
DavidNJ, your point 3 is flat out wrong. A reduction in unsprung mass has an impact that is much greater than a commemsurate reduction in sprung mass.
You think so? Find a credible engineering reference that says that (other than pop culture auto mags) or work out the equations yourself (not that hard for single wheel in a simple model); it is just two parallel spring dampers in series with a ground reference and a mass on either side. You can use capacitors for mass, resistors for dampers, inductors for springs and model in in LTspice or Matlab.

Or better, how about some empirical evidence. Is there someone here who replaced their wheels with wheels 10# lighter while keeping the tires the same? Did they seem a ride or handling difference?

demas, what are the roads like around Tokyo and in Japan in general? Smooth or US-like potholed and heaved? Do you have IAS?

The Primacy HP is a low performance (in the US "grand touring summer") tire that was in some 3-series sizes that BMW got Michelin to also make in a 5-series 19" sizes, including the M-Sport staggered 19" sizes. My guess is they did that because the softer low performance passenger car tire was less stiff in RFT low-profile size. That accounts for your ok ride. My guess is the PSS tires would be night and day with a similar ride.

In the US, virtually all low performance passenger car tires are all-season. This is a summer tire without low temperature capabilities.

Last edited by DavidNJ; 07-15-2013 at 11:57 AM.
Reply With Quote
  #47  
Old 07-15-2013, 12:27 PM
swajames swajames is offline
Officially Welcomed to the 'Fest
Location: Silicon Valley
 
Join Date: Jan 2005
Posts: 996
Mein Auto: Jaguar F-Type V8 S
Funny how you post a thread asking questions, yet seem to know all the answers....

You have members here who have made the changes in question, and you'll find plenty of information about the benefits of reducing unsprung mass should you care to look.

Should you choose not to follow the good advice herein, it's your loss.
__________________
2014 Jaguar F-Type V8 S
Range Rover HSE Lux, Orkney Gray, Sand interior
Porsche 911 Carrera S Convertible, Midnight Blue, 6-Speed
BMW 550i, BMW 545i
Reply With Quote
  #48  
Old 07-15-2013, 01:01 PM
DavidNJ DavidNJ is offline
Just Confused...
Location: Warren, NJ
 
Join Date: Apr 2004
Posts: 310
Mein Auto: 01 530i; 04 S2k; 94 Supra
Quote:
Originally Posted by swajames View Post
Funny how you post a thread asking questions, yet seem to know all the answers....

You have members here who have made the changes in question, and you'll find plenty of information about the benefits of reducing unsprung mass should you care to look.

Should you choose not to follow the good advice herein, it's your loss.
I didn't know the answers...but I learn quickly. "Unsprung weight" is one of the popular misunderstandings, I challenge you to find a wheel only change that had a discernable difference. On same race cars they go crazy with this stuff. Magnesium hubs. Titanium brake discs. Aluminum lug nuts. But it is all about rotational inertia; how quickly the car accelerates or stops.

If you think there is a post anywhere where it was unsprung weight only (a wheel change without a wheel width, offset, tire, or suspension change) that had an affect on ride or handling, post it. If you have a serious technical article where someone did the test, post it.

Yes...I know more than a casual amount about automotive suspensions. However, the whole issue of RFTs in the BMW was a void to me. I now can wind my way through the posts, fit them into context.

I'm very interestd to see how the Q50 fairs on the Infiniti forums this fall. It appears the sport model will have BMW sized 245/40-19" runflats. Should prove interesting. My educated guess is they will have lots of wheel and tire failures, similar to the BMW owners. Since the car may be a few hundred pounds lighter, maybe the problem will be less severe. Note: Infiniti is shipping them initially with an "optional" spare tire.

The standard model Q50 has 225/55-17s. MB is only using 245/45-17s on their runflat diesel and hybrid E-class models. BMW F10 owners with 245/45-18 tires haven't reported any failure problems in another thread here. Empirical data.
Reply With Quote
  #49  
Old 07-15-2013, 01:12 PM
DavidNJ DavidNJ is offline
Just Confused...
Location: Warren, NJ
 
Join Date: Apr 2004
Posts: 310
Mein Auto: 01 530i; 04 S2k; 94 Supra
I almost forgot, the reason I was on was to post this:

Reply With Quote
  #50  
Old 07-15-2013, 01:24 PM
swajames swajames is offline
Officially Welcomed to the 'Fest
Location: Silicon Valley
 
Join Date: Jan 2005
Posts: 996
Mein Auto: Jaguar F-Type V8 S
Quote:
Originally Posted by DavidNJ View Post
I didn't know the answers...but I learn quickly. "Unsprung weight" is one of the popular misunderstandings, I challenge you to find a wheel only change that had a discernable difference. On same race cars they go crazy with this stuff. Magnesium hubs. Titanium brake discs. Aluminum lug nuts. But it is all about rotational inertia; how quickly the car accelerates or stops.

If you think there is a post anywhere where it was unsprung weight only (a wheel change without a wheel width, offset, tire, or suspension change) that had an affect on ride or handling, post it. If you have a serious technical article where someone did the test, post it.

Yes...I know more than a casual amount about automotive suspensions. However, the whole issue of RFTs in the BMW was a void to me. I now can wind my way through the posts, fit them into context.

I'm very interestd to see how the Q50 fairs on the Infiniti forums this fall. It appears the sport model will have BMW sized 245/40-19" runflats. Should prove interesting. My educated guess is they will have lots of wheel and tire failures, similar to the BMW owners. Since the car may be a few hundred pounds lighter, maybe the problem will be less severe. Note: Infiniti is shipping them initially with an "optional" spare tire.

The standard model Q50 has 225/55-17s. MB is only using 245/45-17s on their runflat diesel and hybrid E-class models. BMW F10 owners with 245/45-18 tires haven't reported any failure problems in another thread here. Empirical data.
Tell that to Dunderhi or the countless others - including me - who have switched stock wheels for lighter rims and have noticed a significant improvement in ride and handling.

If you refuse to accept that reducing unsprung and rotational mass can positively benefit ride and handling that's your call. Wiser heads know appreciate and notice the difference.
__________________
2014 Jaguar F-Type V8 S
Range Rover HSE Lux, Orkney Gray, Sand interior
Porsche 911 Carrera S Convertible, Midnight Blue, 6-Speed
BMW 550i, BMW 545i
Reply With Quote
Reply

Bookmarks


Forum Navigation
Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 5 Series > F10 / F11 (2011 - Current)
Today's Posts Search
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On



Forum Jump


All times are GMT -7. The time now is 05:54 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
© 2001-2011 performanceIX, Inc. All Rights Reserved .: guidelines .:. privacy .:. terms