[lukeeesteve]

I figured that I would drop a quick note to the forum with a quick thank you for all the information that's been posted. This has made my life a whole bunch easier these last few weeks.

Quick question.....anyone managed to stuff wider tires under her...like 255/45-19 Fronts and 285/45-19 rears. I know the front isn't an issue, but I haven't had a chance to figure out the rears.

[brissim]

For a start you would have trouble using that tyre/tire combination - they are two different overall diameters. If you want to use wider tires on the rear you are going to have to use a lower profile to keep the same overall diameter.

Tony

[F25er]

I thought a staggered setup was a problem for AWD systems hence they're not offered by BMW.

[lukeeesteve]

BMW has an optional 245/45F and 275/40R so that's the fall back plan.

With 255/45F and 285/40R, you will be about 2% taller all around, the vehicle will ride 0.5cm taller (not an issue) and the 2 sizes are within 2 revolutions per mile within each other (0.3% diameter of 2/10" difference). I am assuming that since you can see similar differences as your front and rear tires wear at different rates, that the AWD has enough slop within the system to deal with that.

Some tire brands actually match both tire sizes in the 255/45 and 285/40 combo, So the above variance can be moot with some tire brands/models selections.

The above is based on information on the tire rack.

Also did a little more research and

According to the experts at TireRack, the tires on xdrive cars can be different sizes from original equipment (but must be within 3% of original tire diameter), and they need to be within 1% (not to exceed) diameter size of each other to not cause problems.


Apparently that question has been posed to BMW from other x-drive owners and differences just over 1 % should not pose a problem either.