By keeping them at 32 psi all around, 35 psi when fully loaded, reasonable cornering (it isn't a sports car), no spinning on snow/ice, etc.

I am sure they would have gone another 10,000 miles, but I didn't measure the tread depth when I sold the vehicle so I can't be sure. They didn't look worn too badly. OE 17" Michelin MXV4 all seasons.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue