Wheels/Tires for 4.4i X5?

[X5Baron]

I have a wonderful, fully loaded 2005 X5 4.4i with 19" sport wheels. Unfortunately, with only 38,000 miles I have worn out my SECOND set of tires. Wanting tires that can be rotated (the rear 19" wheels are wider than the front) and that will last longer begs the question...should I buy the smaller standard wheels and tires or is there a better wheel option that will allow longer lasting, rotatable tires while retaining the sport look of the larger wheels? Maybe the 18" wheels from the new (E70) X5?

Any help or ideas would be appreciated!!!

Thanks, Patrick