New 2009 2010 BMW Z4 - ZPOST
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read


Go Back   New 2009 2010 BMW Z4 - ZPOST > BMW Z4 Forum (E89) > 2009-Current Z4 Forum (E89) General Discussion

Post Reply
 
Thread Tools Search this Thread
      01-25-2013, 12:24 AM   #45
InsanePineapple
Shenanigans
InsanePineapple's Avatar
United_States
79
Rep
1,252
Posts

Drives: See Signature
Join Date: Jul 2010
Location: Austin, TX

iTrader: (1)

Quote:
Originally Posted by VailM3 View Post
So is it basically the RFT causing the damage to these wheels + road conditions. Living in Switzerland i have yet to see a single pothole, when u cross to the french side, different story.
I'm still on stock RTFs but will change them to regular tires as soon as they are worn out. My wheels appear to be fine right now. Texas roads are pretty smooth. Although I cringe every time I accidentally go over a bump in the road. Fingers crossed.
__________________

[Current] Tesla Model 3 Performance
[Retired] Audi R8 V10 6MT, BMW i3 BEV, BMW i3 REx, BMW Z4 sDrive35i DCT, BMW 335i Coupe 6MT
Appreciate 0
      01-25-2013, 09:25 AM   #46
Mr. ///M3 RD
Happy Camper
Mr. ///M3 RD's Avatar
Canada
612
Rep
7,869
Posts

Drives: C63 AMG & 280 SL on Weekends :
Join Date: May 2010
Location: GTA, Ontario - Canada

iTrader: (0)

Garage List
And the story continues ... I wonder if it be worth while to write to the top dog of BMW that mails me the fine BMW magazine and tell him the story of my two rear cracked 296 wheels and how I got royaly screwed over by BMW.

Nah ... I think it be a waste of time ... Bet he has many letters like it.

Sorry to see so many of my former Z4 friends also now have the 296 cracked wheel syndrom. Someone PM me details of that re-designed wheel, perhaps I should write that letter to the top dog of BMW ... Who knows he may even authorize to cut a cheque of $800- that I was screwed out off by BMW. Hahaha
__________________
Cheers, Rolf-Dieter

Life will take us to some interesting places, fortunately The ///M3 will too with a many of us know this very well, now my C6.3 AMG with 487 HP does it too
---> Click here for some good stuff I found
Appreciate 0
      01-25-2013, 01:03 PM   #47
blschaefer1
First Lieutenant
blschaefer1's Avatar
United_States
205
Rep
393
Posts

Drives: 2022 X3 xDrive 30i
Join Date: Jun 2011
Location: Prescott, AZ

iTrader: (1)

Quote:
Originally Posted by Pacemaker1000 View Post
Just checked and I have the newer/modified wheels
Does this mean I am exempt from cracking?
I too have 296's. I just purchased the car new in November. How can I tell if mine are the newer/modified design?
Appreciate 0
      01-25-2013, 08:46 PM   #48
HerrK
Captain
HerrK's Avatar
40
Rep
640
Posts

Drives: 21 X5 40i, 77 R100Rs
Join Date: Dec 2009
Location: AZ

iTrader: (0)

If you go to this post in the hyperlink you will see the shallow center drop (step) on the older style (Top photo) vs the larger center drop (step) on the newer design (Bottom Photo). The larger center drop increases the cross sectional moment of Inertia and decreases the Hoop stress at the outer edge where the rubber meets the rim and the cracks develope. This is especially important at the inboard side of the rim, as there are no spokes as in the outboard side. Less support = higher bending stresses. Since I won't get my old cracked wheels back I won't be doing any destructive evaluation of rim. I still theorize that minor manufacturing flaws in the castings combined with repetative bending stresses eventually leads to a fatigue crack. This along with the impact loads (hitting a bump or pot hole) imparted by the stiff side wall of the RFT tranfered to the rim combine to propagate the crack growth.


The fatigue life of a component can be expressed as the number of loading cycles required to initiate a fatigue crack and to propagate the crack to critical size. Therefore, it can be said that fatigue failure occurs in three stages – crack initiation; slow, stable crack growth; and rapid fracture.


http://e89.zpost.com/forums/showthre...=643047&page=2
__________________

HerrK - 2021 X5 40i M Sport l PCD l Atlantis Blue/Ext'd Tartufo Merino l M Sport w/blue Calipers l Matt Popular l HK Sound l 740's l Exec & Drive Pro Pack
Sold w/Great Memories - E89 Z4 l ED 2010 l 2011 35i l Crimson/Ext'd Coral Red w/Alum l 6 sp MT l Prem Sound l Sport Pack l 296's

Last edited by HerrK; 01-26-2013 at 08:23 AM..
Appreciate 0
      01-26-2013, 03:34 AM   #49
VailM3
Captain
61
Rep
769
Posts

Drives: 2011 Z4 35is
Join Date: Jan 2013
Location: Geneva Switzerland

iTrader: (0)

Quote:
Originally Posted by morfinx View Post
I'm still on stock RTFs but will change them to regular tires as soon as they are worn out. My wheels appear to be fine right now. Texas roads are pretty smooth. Although I cringe every time I accidentally go over a bump in the road. Fingers crossed.
So swapping to non RFT will eleviate this issue. What happens when you get that inevitable flat in the middle of nowhere?
Appreciate 0
      01-26-2013, 04:09 AM   #50
InsanePineapple
Shenanigans
InsanePineapple's Avatar
United_States
79
Rep
1,252
Posts

Drives: See Signature
Join Date: Jul 2010
Location: Austin, TX

iTrader: (1)

Quote:
Originally Posted by VailM3 View Post
So swapping to non RFT will eleviate this issue. What happens when you get that inevitable flat in the middle of nowhere?
I carry this in the car:

http://www.amazon.com/Slime-70005-Sa...qid=1359194885

This actually fits nearly perfectly into the cavity in the trunk for the pass through hole.

If it's a severe puncture, I would just call a tow truck.
__________________

[Current] Tesla Model 3 Performance
[Retired] Audi R8 V10 6MT, BMW i3 BEV, BMW i3 REx, BMW Z4 sDrive35i DCT, BMW 335i Coupe 6MT
Appreciate 0
      01-26-2013, 10:07 AM   #51
blschaefer1
First Lieutenant
blschaefer1's Avatar
United_States
205
Rep
393
Posts

Drives: 2022 X3 xDrive 30i
Join Date: Jun 2011
Location: Prescott, AZ

iTrader: (1)

Quote:
Originally Posted by HerrK View Post
If you go to this post in the hyperlink you will see the shallow center drop (step) on the older style (Top photo) vs the larger center drop (step) on the newer design (Bottom Photo). The larger center drop increases the cross sectional moment of Inertia and decreases the Hoop stress at the outer edge where the rubber meets the rim and the cracks develope. This is especially important at the inboard side of the rim, as there are no spokes as in the outboard side. Less support = higher bending stresses. Since I won't get my old cracked wheels back I won't be doing any destructive evaluation of rim. I still theorize that minor manufacturing flaws in the castings combined with repetative bending stresses eventually leads to a fatigue crack. This along with the impact loads (hitting a bump or pot hole) imparted by the stiff side wall of the RFT tranfered to the rim combine to propagate the crack growth.


The fatigue life of a component can be expressed as the number of loading cycles required to initiate a fatigue crack and to propagate the crack to critical size. Therefore, it can be said that fatigue failure occurs in three stages – crack initiation; slow, stable crack growth; and rapid fracture.


http://e89.zpost.com/forums/showthre...=643047&page=2
Thanks. Just checked and I have the new design in the rear. Plus I'm running non-RTF Michein Pilot Super Sports. Hopefully I will be OK.
Appreciate 0
      01-26-2013, 01:24 PM   #52
HerrK
Captain
HerrK's Avatar
40
Rep
640
Posts

Drives: 21 X5 40i, 77 R100Rs
Join Date: Dec 2009
Location: AZ

iTrader: (0)

Quote:
Originally Posted by blschaefer1 View Post
Thanks. Just checked and I have the new design in the rear. Plus I'm running non-RTF Michein Pilot Super Sports. Hopefully I will be OK.
Got the car back today and HURRAH! - I now have the "NEW" design as well. I was able to measure the step down, that previously was 3mm at most is now 13mm. That is a huge difference in the stiffness capability over the old design. I have no doubt that, even with using RFT, the new design rim would take substancially more abuse before failure, it might bend before cracking. I have no cornerns or worries about any cracking issues using the Non RFT's with the new design.

Shame on BMW for not making this a "Voluntary Safety Recall"
__________________

HerrK - 2021 X5 40i M Sport l PCD l Atlantis Blue/Ext'd Tartufo Merino l M Sport w/blue Calipers l Matt Popular l HK Sound l 740's l Exec & Drive Pro Pack
Sold w/Great Memories - E89 Z4 l ED 2010 l 2011 35i l Crimson/Ext'd Coral Red w/Alum l 6 sp MT l Prem Sound l Sport Pack l 296's
Appreciate 0
      01-26-2013, 01:42 PM   #53
ManiacGT
Major
ManiacGT's Avatar
United Kingdom
84
Rep
1,448
Posts

Drives: Z4 sDrive 35i
Join Date: Jan 2011
Location: Manchester, UK

iTrader: (0)

They're not actually 10mm deeper in the metal... they've simply added a lower step to the inner edge. This increases rigidity (like ribs in roofing materials). Both my rears were replaced before this new design came out so unfortunately for me I can see my having to replace them again eventually
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 Off



All times are GMT -5. The time now is 06:59 PM.




zpost
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST