can someone please tell me what size spacers I would need for my front and rear wheels, so that the 8 x 18 front and 10 x 18 rear wheels sit flush with the wheel arches.

My car is is the 2001 911 996 Carrera Cabriolet 3.4litre narrow body. The wheels are OEM GT3 Sports Design 8 x 18 front and 10 x 18 rear, the tires are 225/40/zr18 and 285/30/zr18

also would i need new wheel nuts or will my exist nuts still fit

Thanks

Shane