If both tires are wearing (not cupping, just wearing) on the outer edge of the fronts then I would look to aggressive cornering as a likely cause, on top of any suspension issues. A heavy vehicle like the X5, understeering, will wear outer edges first.

__________________
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