[KmanM3]

I have a set of 19" 437M wheels on their way but they have the stock M4 tire sizes of 255/35 front and 275/35 rear, which will not be compatible with Xdrive.

Wheel specs are:
19x9 ET29
19x10 ET40

Since the existing tires are basically brand new it would be nice to keep either the front or rear sizes intact and just replace one set of tires. What tire sizes could I mix and match with the existing tires to keep my Xdrive system happy?

[.BMW.]

245/40-19 front (275/35-19 is OEM rear size for F10).

[KmanM3]

Originally Posted by .BMW.

245/40-19 front (275/35-19 is OEM rear size for F10).

Thanks, that is what I was thinking. I don't want the tires to be too stretched though and prefer as much lip coverage as possible so that is why I was hesitant to go with a 245 but maybe that will not be an issue.

[.BMW.]

The tires will be slightly stretched. But you can not avoid that if you like to reuse either the front or the rear tires.

Widest tires that fit on the wheels and works with xDrive would be 255/40-19 front and 295/35-19 rear. But that's a more expensive option with four new tires.