I'm to to sure if this applies for WA roads to but we arn't alowed anything larger than two sizes width or height. i have 18's by 7.5 with 215x35 tyres on my 93 civic hatch and after alot of times getting yellow stickered, 12 times in one yr actually i asked why i couldnt get a permit for my 18's at the pitts and the inspector said i dont see why you couldnt. soo that day i got permits and ever since ive showed the permits to the 'five ohh' and they've left me alone