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@alsd.... that dia of 255/45/18 rear is 26.7" dia
245/45/18 front is 27" dia

This is probably your problem

Also, check the tire pressures. Different pressures will produce different dia's. The Xdrive cars like the same dia front & rear.
 

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Ok great so, now I’m just thoroughly confused.

What Tyre sizes would you guys say is the correct combination then?


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Ok great so, now I’m just thoroughly confused.

What Tyre sizes would you guys say is the correct combination then?


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Go to a site like Tire rack or Discount tire & put in your car information & see what tire sizes they recommend. They are pretty good at it. Also, the owners manual will show what sizes, even offsets that are recommended for your X3
 

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IMG_0035.jpg

Here is my Tyre placard in the door jamb. According to that my Tyre size combination is correct at 235/50/18 front and 255/45/18 rear so if that’s not correct then I don’t know what to do!!

As for brand, well I’ve already forked out for the rears so I’ll have to go the same brand on the rear which is now organised and will be fitted.

Now that I think about it and after all of your inputs it makes sense. With differing Tyre diameters, the system thinks it’s constantly slipping just a fraction and hence why the problem is so bad on hills.

Thanks guys and duke, fingers crossed I haven’t cooked it!




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And if I shouldn’t stagger my tyres, what am I supposed to put on? The OEM says that my tyres should be exactly was there are now so I’m confused.


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I don’t recall the X3 coming with staggered tires from factory. Where do you read or see this?


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I don’t recall the X3 coming with staggered tires from factory. Where do you read or see this?


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Gday Jeepo,

Well that picture is from my door, so that’s the first place.

Second, it’s an m-sport package so she’s got m-Doppel spoke rims etc.

I’m guessing that most of you guys are in the states, I’m Australia so we probably got different models and specs to you guys hence the staggering stuff.


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As mentioned, the placard only applies to a specific set of tires from a specific manufacturer or 2. If the brands and wear differ, you may as well have different sized tires on it. Your “thinking on it” is exactly correct. Tires MUST be equal size and wear within 1%. Do that and your problems should go away, assuming you haven’t caused irreparable damage to the transfer case.

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My M-Sport came with OEM staggered tire and wheel sizes too.
 

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As mentioned, the placard only applies to a specific set of tires from a specific manufacturer or 2. If the brands and wear differ, you may as well have different sized tires on it. Your “thinking on it” is exactly correct. Tires MUST be equal size and wear within 1%. Do that and your problems should go away, assuming you haven’t caused irreparable damage to the transfer case.

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Yep fingers crossed!


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Ah bugger!

Well I can’t go wrong if I follow the tyre placard.

I’m just surprised at how changing tyres on the rear but not the front has had such a detrimental effect.

I really hope that having fresh rubber all round helps this.


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Ah bugger!

Well I can’t go wrong if I follow the tyre placard.

I’m just surprised at how changing tyres on the rear but not the front has had such a detrimental effect.

I really hope that having fresh rubber all round helps this.


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It probably makes more sense the issue occurs with the rears because that’s where 70% of the torque is going. I’m surmising here, but if the vehicle “thinks” there’s slippage at the front, it’ll shift torque to the rear, lessening any binding. With it “thinking” the rears are slipping, it’s transferring more torque to the front axle that doesn’t need it, and you feel the binding as the two axles fight each other. One thing is definitely certain, catastrophic damage will occur somewhere because of it, most like the TC clutches first. As soon as you get a proper set of spec spec tires on the thing, you’ll need to change the T case fluid ASAP because the more you drive it, the more the fluid turns to sandpaper. Use only the BMW fluid or a fluid meeting its specs (I have Shell S tec in mine which I believe is the OE supplier and it’s been fine).


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So I had the front tyres installed today. Same brand (no not the BMW recommended brands, just bought a house and am literally too poor to afford that level of investment right now!) and all according to spec.

Whilst it’s not as bad. The problem remains.

I’m going to change the TC oil and then get the adaptations reset but after that I’m outta ideas.

Ready to set the fu$king thing on fire now.


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Have you reset the SAS? And checked/cleaned the wheel speed senders and their reluctor rings?
 

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I have not!

I’ll give it a try. I got so caught up in this tyre business that I forgot all about your recommendation!

Will give it a go and see how we go with that.


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