Wide tires have the same area footprint as narrow tires, it is just a different shape, namely wider and not as long.

Depends a lot on the type of sand, and your driving techniques.

I'll let others chime in on how it does with those specific tires. Some of our Australian posters have the most experience with this.

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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