The Dreaded Cracked Alloys

[Smartbear]

Hi, my wheel cracked in a new place & the existing weld was intact.
You did better than me with the new wheel discount, I was offered 10% off! The uk seems to fare much worse than other countries for this issue, I think our appalling roads are a large factor :x
Rob

 

[ronk]

...... I think our appalling roads are a large factor :x
Rob

In France and Germany Ive seen signs warning of poor road surfaces ahead - these poor road surfaces are often better than our normal potholed excuse for roads.

If Euro can do it, why can’t we?

 

[RustyZ4]

...... I think our appalling roads are a large factor :x
Rob

In France and Germany Ive seen signs warning of poor road surfaces ahead - these poor road surfaces are often better than our normal potholed excuse for roads.

If Euro can do it, why can’t we?

You ought to drive in some parts of Italy, make our roads look smooth

 

[pbr67_zed]

Just collected my car after it went in for a brake fluid change and a complementary "health check". They found a crack in one of my (19" 296) rears. No issues with losing air yet. Car was from an independent dealer, so no chance of a warranty covering the wheels.

Tiny, tiny, silver lining - the (non-BMW) garage couldn't get their equipment to reset the brake fluid service indicator, so gave me the fluid change for free! Might cover the cost of welding the wheel I suppose

 

[ronk]

I have a suspicion that these cracks are not due to mechanical damgage and are due to internal manufacturing stress ?

 

[Smartbear]

I have a suspicion that these cracks are not due to mechanical damgage and are due to internal manufacturing stress ?

It’s strange how most of the instances are to wheels fitted with runflats though Ron, they must be contributing to the failures? :?
Rob

 

[Busterboo]

It’s strange how most of the instances are to wheels fitted with runflats though Ron, they must be contributing to the failures? :?
Rob

Are the runflat tyres so hard that they crack the wheel, Rob?

 

[Smartbear]

It’s strange how most of the instances are to wheels fitted with runflats though Ron, they must be contributing to the failures? :?
Rob

Are the runflat tyres so hard that they crack the wheel, Rob?

I think that they don’t help an already fragile wheel survive in arduous conditions, it’s not just one thing but a combination of elements, just my opinion of course as I’m not a scientist
Rob

 

[Busterboo]

Do you think runflats allow wheels to touch the ground? The edges of potholes, for example?

(Were there signs on your cracked wheels that they'd touched the ground?)

 

[dario]

The simple fact in my opinion is that the wheels are manufactured weak. the load imposed on the inner edge is high given that the outer edge is supported by the spokes etc.

when mine turned up with 2 cracked wheels on the rear and it was going to cost me £1,100 to replace them....... to replace them again in the future i thought "I SHOULD COCO".

I bit the bullet and purchased some real wheels from a real wheel manufacturer.

my thread with the BBS wheel replacement https://z4-forum.com/forum/viewtopic.php?f=23&t=95023

 

[Smartbear]

Do you think runflats allow wheels to touch the ground? The edges of potholes, for example?

(Were there signs on your cracked wheels that they'd touched the ground?)

I think the runflats are so unyielding, that there’s less chance of them deforming enough to let the wheel contact the ground.
My wheels showed no impact damage apart from the cracks
Rob

 

[dario]

Do you think runflats allow wheels to touch the ground? The edges of potholes, for example?

(Were there signs on your cracked wheels that they'd touched the ground?)

I think the runflats are so unyielding, that there’s less chance of them deforming enough to let the wheel contact the ground.
My wheels showed no impact damage apart from the cracks
Rob

In my opinion the inside edge of the wheel constantly deforms and eventually that constant deformation manifests itself as a crack when the mailability of the metal reaches a point where it cries enough. the inside rim on the BBS wheels i bough at 2-3 times thicker than the BMW option. much more rigid.