Sorry mate, but your wrong with that statement....All tyre size regulations are identical throughout Australia and have been for 15 years or so....The reason being is, a tyre shop is responsible for ensuring a tyre/s fitted to a vehicle is legal, otherwise if the vehicle is involved in an accident anywhere in this country, and the tyre shop is found to have fitted the incorrect tyre/s to the car, they are responsible for all damages....They are also responsible to ensure the car is roadworthy with tyre/s....Again, if the car is defected as a result of an incorrectly fitted tyre/s, the tyre shop is responsible for the costs of replacing the tyre/s and removing the defect for the tyre/s.
Why do you think you can have your tyre/s replaced anywhere in Australia, regardless of where the car is registered?