please see the following
http://www.infrastructure.gov.au/roads/vehicle_regulation/bulletin/pdf/NCOP11_Section_LS_Tyres_Suspension_Steering_V2_1Jan_2011%20v3.pdf specifically page 19
before you try and rebut my comment. this is the NCOP it has now as far as i am aware been adopted by EVERY state in Australia i believe only 2 states have made amendments SA and QLD. (qld's amendments mostly relate specifically to testing procedures and are irrelevant for the purpose of this conversation)
now
the +2inch rule has bee circulating for some time and i can equivocally tell you it's bogus! if you want to fit big fat 22" rims you can provided you can find rubber bands small enough to keep the overall rolling diameter within the +15mm -26mm rule for class ma motor vehicles
as listed here (from the above source)
[SIZE=13.5pt]4.2.4 Overall Nominal Diameter[/SIZE]
[SIZE=13.5pt]The overall diameter of any tyre fitted to a passenger car or passenger car derivative must not[/SIZE]
[SIZE=13.5pt]be more than 15mm larger or 26mm smaller than that of any tyre designated by the vehicle[/SIZE]
[SIZE=13.5pt]manufacturer for that model.[/SIZE]
[SIZE=13.5pt]The overall diameter of any tyre fitted to:[/SIZE]
[SIZE=13.5pt]4WD passenger vehicles specifically designed for off-road use (typically MC ADR[/SIZE]
[SIZE=13.5pt]category).[/SIZE]
[SIZE=13.5pt]All wheel drive[/SIZE]
[SIZE=13.5pt](AWD) vehicles including those AWD vehicles that may be[/SIZE]
[SIZE=13.5pt]certified as MC ADR category, (also commonly known as[/SIZE]
[SIZE=13.5pt]soft roaders)[/SIZE]
[SIZE=13.5pt]are not[/SIZE]
[SIZE=13.5pt]included in this category;[/SIZE]
[SIZE=13.5pt]4WD goods vehicles and their 2WD equivalents if the chassis and running gear are[/SIZE]
[SIZE=13.5pt]essentially the same as the 4WD version (N ADR category); or[/SIZE]
[SIZE=13.5pt]any medium weight goods vehicle (NA2, NB ADR category).[/SIZE]
[SIZE=13.5pt]Must not be more than 50mm larger or 26mm smaller than that of any tyre designated by the[/SIZE]
[SIZE=13.5pt]vehicle manufacturer for that vehicle.[/SIZE]
[SIZE=13.5pt]Note[/SIZE]
[SIZE=13.5pt]: Increases in tyre diameter are subject to compliance with all other requirements[/SIZE]
[SIZE=13.5pt]specified under this clause (Clause 4.2[/SIZE]
[SIZE=13.5pt]Non-Standard Tyres and Rims)[/SIZE]
[SIZE=13.5pt]and may[/SIZE]
[SIZE=13.5pt]therefore be limited by other factors such as insufficient clearance.[/SIZE]
[SIZE=13.5pt]Speedometer accuracy must be maintained for the selected tyre and rim combination to within[/SIZE]
[SIZE=13.5pt]the degree of accuracy specified in ADR 18 where applicable. It is suggested that the degree of[/SIZE]
[SIZE=13.5pt]accuracy is in accordance with the most recent version of ADR18.[/SIZE]
