[cdmulders]

Originally Posted by Riddleryan

Thanks, brother!

I saw the www.wheel-size.com suggestions before. It made me believe it wasn't possible. But looking at your tiresize.com link, says it might be. +1.1% difference.
Think I need spacers for such a difference or no?

Riddleryan, I must admit that I'm not understanding what you are hoping to accomplish. As ezaircon4jc stated, there is no correlation between spacers and tire / wheel size per se, except for the location inboard or outboard of the wheel with respect to suspension and fenders.

If you are suggesting to go with a square setup (as you initially stated), then with four identical wheels and tires, your xDrive will not even notice the difference, so you can go to 255 vice 245 width tires (all around), since front and back will be the same. Having said that, I'm not sure what advantage you are anticipating by increasing the width of your tire tread by only 10mm (less than 1/2 inch). If you wish to change the ride and/or ability to absorb bumps, then you would need to change (and raise) the ratio of your tire, from the stock 45 to something like 50. I ran winter tires with 245/50/18 specs (on 18 inch wheels obviously) on my xDrive with no issues whatsoever. The car was not lowered, however.

What exactly are you intending to accomplish?

Cheers.