[Andy3661]

Been reading up on tyre change on a xdrive.

Should all 4 be changed at the same time as the rear are significantly more worn than front?

Various people online say that different tread depth on front and rear can cause problems.

[Dark_cobra]

By that thinking any time you got a puncture you'd need to fit 4 brand new tyres?

[Tam the Bam]

Originally Posted by Andy3661

Been reading up on tyre change on a xdrive.

Should all 4 be changed at the same time as the rear are significantly more worn than front?

Various people online say that different tread depth on front and rear can cause problems.

I’m pretty sure there is a difference in tyre thread depth limit for Xdrive . Check with your dealer...

[JNW1]

Originally Posted by Andy3661

Been reading up on tyre change on a xdrive.

Should all 4 be changed at the same time as the rear are significantly more worn than front?

Various people online say that different tread depth on front and rear can cause problems.

Problems have been reported with transfer boxes when the tyre wear is significantly different front to rear so I suppose the question is how much more tread than the worn fronts will a new set of rears have? Up to a couple of mm you're probably ok but more than that and personally I'd consider changing the full set.

As an aside, experience with my F31 335d X-drive was that all four tyres tended to wear at pretty much the same rate so I'm surprised you're in a situation where the rears have worn much more quickly than the fronts. Too early to tell with my G21 but perhaps the X-drive set-up is different on the newer model with the tyre wear different as a consequence?

Originally Posted by Dark_cobra

By that thinking any time you got a puncture you'd need to fit 4 brand new tyres?

Not if you have four relatively new tyres on the car but if they're all (say) half worn then potentially yes, if you get a puncture in one it might be wise to replace the full set on an X-Drive car. Of course this all assumes you're going to be keeping the car for a while - if you're not then you may be happy to take the risk mixing new and part-worn tyres on the basis any resultant drivetrain issue will be a problem for a subsequent owner.....

[Soul_Glo]

Yes problems do occur with the transfer box as it is sensitive to tread depth. If the tread is below 2.4 mm it make the box work harder. So all need to be above 2.4 mm in tread depth. Just change the ones that need to be done. Ideally match the tread pattern and brand on the same axle. However, if one is worn and the other is fine then it's not a big deal. I have had x drive with one tyre at 4 mm and one at 7 mm and it was fine but it was the same tread pattern and model.

[ramparts]

Originally Posted by Soul_Glo

Yes problems do occur with the transfer box as it is sensitive to tread depth. If the tread is below 2.4 mm it make the box work harder. So all tyres need to be above 2.4 mm in tread depth. Just change the ones that need to be done. Ideally match the tread pattern and brand on the same axle. However, if one is worn and the other is fine then it's not a big deal. I have had x drive with one tyre at 4 mm and one at 7 mm and it was fine but it was the same tread pattern and model.

I never let tyres get anywhere near 2.4mm depth!