Originally Posted by Qsilver7

In regards to the 8x18 vs 8.5x18 wheels...an extra 1/2" width won't matter...my 2006 e53 has the style 153 18" wheels and it came with 255/55/18 tires. and 8" or 8.5" width wheel can easily be mounted with a 255/55/18 tire.

As far as using any of the e53 19" wheels...that wouldn't be an issue either...as long as you install the correct 19" tire (see the label I posted previously). Basically you can see that all e53's can use the same 18/19/20 inch wheels & tires. The 17" wheel/tire combo won't fit on the 4.6is & 4.8is.

The 19" tire on your door jamb is identifying the small donut spare that the 4.6is & 4.8is came with (as well as it's higher tire inflation pressure).

Here's a link to the BMW e53 wheels (and many of the other BMW wheels) which also gives specs: All BMW wheel styles X X5-E53 | BmwStyleWheels.com