Diff failure,,,caused by tyres,,??

[plowy]

My 55 plate 3.0D has destroyed a driveshaft and I imagine the diff judging by the noise lack of drive and the shaft is dislodged,,,this has occurred in just normal driving about 100 miles after fitting new rear tyres, the tyre story is that a full set of khumo k17,,I think,,have done 16000 faultless miles and the rears needed replacing,,reading ok things about the Accelera brand on the X5 I thought we shall have a go with them, my wife drives the car mostly in a steady manner, the front Khumos have about 3/4 mm left and with MOT time end of October plan was to match the fronts with the acceleras,,so..the diff/driveshaft lets go big style.....have BMW comprehensive warranty and its going in tomorrow......it's very ironic given the tyre change....your thoughts....??

And please it's not a " you dont wanna be doing that,,,budget tyres ooooohhhh,,,,"..... You know what I mean

[Steamyrotter]

Unlikely to be tyre related.

Probably would have gone anyway....

The way the car was raised and wheels fitted may have an impact but unlikely
There was probably an underlying issue there just waiting for an excuse to cost you pennies

[plowy]

Master tech fiend tells me....Non star rated, rolling radius outside tolerance puts a lot of stress on the drivetrain and  Xdrive system is very sensitive to it....

Expand your theory on the way the car was raised and wheels fitted..???.....can't grasp any significance there...

[X5Sport]

+1 on something was lurking and waiting.  The OEM Diamaris are made for the X5 (hence the * mark on them) but what the difference is I don't know.

Now as for budget tyres.....well, let's see.  That's a really b........ O:-)

You drive on what rubber you're happy with....   At least it's under warranty.  I have seen comments about rolling radius, especially if changing only one pair, but I can't think of any other incidents like yours on this site.

Richard

[535dboy]

Andy?

[mikem]

Woody ??

[X5Sport]

Buzz???

[plowy]

Yes James.....

[plowy]

Got real excited then...saw 6 thread replies and thought there was some constructive answers...!!!

[535dboy]

How do?

Absolutely no chance of me offering anything constructive I'm afraid but sorry to hear of your woes!

[mikem]

People like you that push up the cost of my warranty.

Fucking Yorkshire Tyres !

[mikem]

J, I'm disapointed. You could e at least put a picture of the RS4 up and said buy one of these instead.

[Nat]

Hi,

I don't think the tyres had anything to do with it. What is sometimes suggested is axle wind. Imagine your back axle, with one 17 inch tyre on one side and one 20 inch tyre on the other. As you drive along the side with the 17 inch wheel will have to go round more times than the other side because of its smaller rolling diameter. That causes the axle to wind itself up. Usually you feel the axle " hop " , normally on very tight slow turns ( like when doing a 3 point turn ) . Thats the axle un-winding itself. In extreme cases like the extreme example I just gaave you ( 17 inch ag 20 inch wheels ) the axle will wind itself to the point of failure if it is a LSD. Normal axles dont suffer from axle wind as just going round corners the outer wheel has to travel further than the inside wheel and thats normal. Now some cars are very sensitive to axle wind. I know a friend who had an issue with a tuareg. Having a bald tyre on one side and a brand new one on the other side gives you a difference of 7-8mm rolling diameter. On some cars that can be enough to cause axle wind, but I have never heard of it on  Bmw's. My Jeep Grand Cherokee was very prone to it, but on tight turns it regularly un-wound itself and was never a problem.
I cant see that having 2 new tyres fitted accross the same axle has in any way caused your issue , unless of course they jacked your car up on the drive shaft or something stupid like that.

Regards,

Nat.

[plowy]

Ok Nat what about this...  I got a length of string and wrapped it round the worn fronts then cut it to length... When the same length of string is wrapped round the new rear tyres it falls short of meeting up by 60mm...my master tech tells me thus is deffo what caused the diff to explode as its all to do with his the Xdrive system reacts to the differing rolling radius of front to rear axles... What's your thoughts on that...???

[mikem]

90% of that 60mm will be down to the difference between a new tyre and a worn tyre, doing the maths shows that a difference in diameter of 12mm gives a difference in circumference on ~ 50mm on an X5 sized wheel.

The other 10% is no doubt down to the difference between manufacturers.

So I think the biggest issue is brand new on one axle and well worn on the other more than mixing brands or using non * approved. Sure I've read that all 4 should be replaced if there's going to be a difference of more than 4mm but how many people observe this, especially as the cars become older/cheaper ?

I just can't believe that it would do catastrophic damage like that within the space of 100miles. There's warnings about not using a suspended tow but nothing about how long the spare wheel can be used for. So you'd assume the system can tolerate a slight deviance.