I'd say there's a very good chance you can get the 255/55/18 Proxes ST II's that I got for under $800 out the door. I got my set down here at Les Schwab for $741 out the door, including the siping. I'm about 3K miles in and they are very good thus far with almost no visible wear. Very quiet as well.

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2013 X5 xDrive3.5i Premium
2002 530I Sport Package
2001 X5 4.4i
2001 M3