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Horror of the week 19/11/10


Tony
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Vehicle BMW X5

 

Index 2007

 

Complaint

Inner rear tyre wear

 

History

We see many X5's with the same complaint but i don't think i've documented this before in HOTW.

 

The chassis

The X5 rear camber/ toe positions are unremarkable since we are talking 4X4

 

The problem

The problem is the RFT ( Run Flat Tyre ) these tyres cannot adopt the rear camber position suggested by BMW simply because the camber position needs to distort the tyres inner sidewall, the RFT sidewall remains the same circumference inside and out and loads the inner wall with the vehicles weight.

 

The evidence

post-2-1290198920.jpg

 

post-2-1290198935.jpg

 

The data

The data images displayed are not to distant from the BMW idyllic positions

post-2-1290199006.jpg

 

post-2-1290199017.jpg

 

post-2-1290199028.jpg

 

The solution

We don't use BMW's positions, over time and research we have developed new positions that allow the contact patch to be undistorted, this stops the Tyre wear and although the camber positions are reduced it increases the grip coefficient because the contact patch is undistorted.

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So in other words what you are saying is that run-flats are pants as they cant adopt BMW`s geo positions.? would it resolve the inner tyre wear if the tyres were NON run-flats.? so letting the tyre wall compress.? to allow for the geo positions.? :bananapopcorn:

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So in other words what you are saying is that run-flats are pants as they cant adopt BMW`s geo positions.? would it resolve the inner tyre wear if the tyres were NON run-flats.? so letting the tyre wall compress.? to allow for the geo positions.? :lol:

 

It would be fine.

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or more importantly BMW choosing to use run flats should have made considerations in the geometry

 

In many countries run-flats will be mandatory, so BMW are compiling, but seemingly they are not making geometric considerations..... we are.

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or more importantly BMW choosing to use run flats should have made considerations in the geometry

 

In many countries run-flats will be mandatory, so BMW are compiling, but seemingly they are not making geometric considerations..... we are.

 

Don't forget BMW suspension is designed for run-flats..... :lol: often quoted by BMW. Nah, they can't be wrong. :lmaosmiley:

 

I've seen pictures like above, where the tyre has seperated. Get the warning 'bong' and 5 miles further on, total tyre failure. So looks like the X5 had a very close call before failure. Also seen pics where it looks the same as above, but with a flat and the owner was praising the run-flat as it 'probably saved his life'.

 

Don't think everyone using the run-flat is getting, that without very close inspection, run-flats are contributing to premature tyre failure.

 

HighlandPete

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We are told the suspension is softer to accommodate the RFT but when normal tyres are fitted the ride improves :lol: Pre/ post RFT tyres the sport geometry positions remain the same, although this savage tyre wear issue only exists with the RFT.

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  • 5 weeks later...
It's just not something you would expect from a top builder.

They are no better than any other manufacturer from a design standards point of view. Probably no worse than most though.

 

 

My bro has an X5, I will, of course, get him to check him tyres - was this fronts or rears?

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It's just not something you would expect from a top builder.

They are no better than any other manufacturer from a design standards point of view. Probably no worse than most though.

 

 

My bro has an X5, I will, of course, get him to check him tyres - was this fronts or rears?

 

Rears, historically the fronts are fine.

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  • 1 month later...
Vehicle BMW X5

 

Index 2007

 

Complaint

Inner rear tyre wear

 

History

We see many X5's with the same complaint but i don't think i've documented this before in HOTW.

 

The chassis

The X5 rear camber/ toe positions are unremarkable since we are talking 4X4

 

The problem

The problem is the RFT ( Run Flat Tyre ) these tyres cannot adopt the rear camber position suggested by BMW simply because the camber position needs to distort the tyres inner sidewall, the RFT sidewall remains the same circumference inside and out and loads the inner wall with the vehicles weight.

 

The evidence

post-2-1290198920.jpg

 

post-2-1290198935.jpg

 

The data

The data images displayed are not to distant from the BMW idyllic positions

post-2-1290199006.jpg

 

post-2-1290199017.jpg

 

post-2-1290199028.jpg

 

The solution

We don't use BMW's positions, over time and research we have developed new positions that allow the contact patch to be undistorted, this stops the Tyre wear and although the camber positions are reduced it increases the grip coefficient because the contact patch is undistorted.

 

 

sorry did i miss something, no specs were changed? did you just toe it in 3mm?

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  • 6 months later...

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