Here is some info for South Australia..
Please read this Link in fullhttp://www.transport.sa.gov.au/pdfs/per ... Height.PDFVehicle Ride HeightVehicle ride height can be increased by any combination of the following three methods. However, it is important to note that a total lift of more than 50mm requires prior approval and a report from a CPE.
Tyres / RimsThe fitting of rims with a different diameter to those listed on the vehicle’s tyre placard is acceptable, provided that the overall diameter of the alternative rim/tyre combination is not greater than 15mm over the largest combination or 15mm smaller than the smallest combination specified on the vehicle’s tyre placard.
If you intend to fit rim/tyre combination outside the 15mm limit, then an application must be made to Vehicle Standards for an Exemption from that particular section of the Road Traffic Act and a report from a CPE supplied with the application.
Any replacement tyre fitted to your vehicle must also have a load capacity equal or greater than the minimum specified on the manufacture’s tyre placard.
SuspensionWhen raising the ride height of your vehicle by changes to the suspension, you must ensure that the original amount of rebound travel is maintained. The rebound shall be limited by the same method as the original manufacturer (i.e. limit straps or shock absorber full extension).
The vehicle ride height cannot be raised by:
•Extended or adjustable shackle plates on leaf springs.
•Relocating a leaf spring on the opposite side of an axle to that of the vehicle manufacturer.
•Spacer blocks mounted above or below the coil spring.
•Wedges or blocks located between the coils.
•Spacer blocks mounted between the top of the suspension strut and vehicle body.
Body LiftThe body of a vehicle can be raised by up to 50mm by the fitting of spacer blocks between the vehicle chassis and body at their mounting points. The blocks must be manufactured from steel, aluminum, or metal of equivalent strength. In some cases the steering shaft may have to be extended as well as longer brake hoses fitted.
If there is any alteration or replacement of the original steering components, then the modification requires prior approval from Vehicle Standards and a roadworthiness inspection upon completion. A report from a CPE may be required
Wheel track (cant find hilux on here but seems to apply)
http://www.sa.gov.au/upload/franchise/T ... 202012.pdfApplication to Modify a Motor Vehiclehttp://www.sa.gov.au/upload/franchise/T ... ehicle.pdfChartered professional engineershttp://www.sa.gov.au/upload/franchise/T ... b%2010.pdf