18s are legal in QLD. Go and get the modifications guidelines from the registry. It states that overall tyre size can not be made larger by more than 15mm. There is 12mm difference between 215/35/18 and standard tyes. This throws the speedo out by less than 2 kms at 100km/h. It is perfectly legal to have these in QLD. The one inch rule applies to NSW. Also not to forget that modifications are only guidelines. An engineer can approve 20s on a corrolla if all the right steps are taken - ie: enough clearance, bigger brakes to compensate for longer stopping distances, etc. Just like engine swaps - not legal except with engineers report. I can get the exact wording of mods from the book if you like? I keep it in my centre consule as ammunition in case I get pulled over in NSW and stuff.