Tires for E70 X5 OEM 21" wheels

[xe70x]

Hi Tire Rack,

I'm considering buying OEM 21" wheels for my 2007 X5 but the factory recommended tires are quite expensive so I'm looking for other tire options. Are there any other brands and/or sizes that fit these wheels at a lower cost?

The wheel sizes are:
Front: 21 x 10
Rear: 21 x 11.5

The factory tires (Dunlop run flats) sizes are:
Front: 285/35/21
Rear: 325/20/21

Thanks,
Johnny