tyre size/transfer case failure

[pedro43]

hi all
just had conformation from BMW specialist in Swansea that my transfer case is defective. Was wondering if anyone has any solid evidence that the transfer case failure is down to non BMW approved tyres ?? the car is running on all practically brand new 245/45-19 fronts and 275/45-19 rears. I understand that I don't know the history of the previous set of tyres and they might have been all sorts and caused the damage, but I'm interested in info going forward. don't want to pay £2000 for repair only for non approved tyres to blow transfer case again. the tyre size fitted are stated on the drivers door jam but I think the original tyres where 17".

many thanks again
peter.

[X5Sport]

Plenty of stories on the Forum where non-star marked tyres have been used, but it isn’t that simple. The risk is higher, but it can depend upon other factors including the physical different in rolling diameter, how the tyres behave under different tyre pressures, tread pattern, wear pattern, difference in wear between wheels and axles - no more than 3mm anywhere.

All anyone can say for certain is that the risk is higher with non ‘*’ marked tyres, but issues are not 100% guaranteed. There have been a couple where ‘*’ tyres have been used, though those are far fewer in occurrence.

If issues do occur they are more likely on staggered wheel sets such as yours. Tyre fitters and garages are becoming more aware of this problem and it isn’t just on BMWs now.

[Leslie]

I guess unless you fit * rated tyres the Bmw warranty on the new case will be void anyway so you haven't much choice !