I think spacers are illegal in Aus.
Try getting new rims and tryes, get a mates car that has the same stud pattern as your car but a bit smaller rims, and see what they do to your car. See if they have any scrub issues..
Also, lift the car up and have a look what it may be scrubbing on, and how badly it is eating through your tyres..
I had a 1007 XR6 Ute on my hoist at work, had 20" bling wheels, lowered, looked hell nice, though the inside of the tyre is worn down to the metal belt of the tyre..