Not sure how to answer that.....Since my 1st X5 I've always had 285's in the rear, this last set of REARS I had to go with 275's.

I cant tell the difference in driving between the 285 and 275 series. and I cant compare to a more narrow tire as I haven't any experience with them.

The only reason I dont like the 275's is the way they LOOK. Silly I know.

I don't run this X5 hard or track it or anything like that. Its a smooth easy drive.

The 3.0 is VERY different that the 4.4....... HUGE difference for me and what I need it for. So I made the move to the 3.0 and its work perfectly well for me. Still have some gitty-up but it doesn't WOW me like the big brother did.