Hi, I've moved from NZ to Perth and want to know if there is a legal restriction on the wheel size you can uprade to from the original wheel size?
Thanks

I think that there "technically" is. However I work in a tyre shop and know first hand that as long as you meet the load and speed ratings you will be fine, they don't care about sizes only meeting the requirements of your vehicle.

I've been told no more than 2 sizes and you have to compensate by a smaller profile to retain the rolling diameter.
You may be able to get away with a bigger diameter if you recalibrate the speedo and have an engineer's certificate for verification.
I may be wrong but I read it somewhere before I made the change.

The man speaks the truth. Gotta keep that rolling circumference very similar so that your speedo doesn't go out of wack.

2" above stock size is legal.

that's bullshit.... i got done for 20" on a car with stock 16".... there is a restriction

from experience:

* the aspect ratio must not vary more than 10 from the front to rear tyres because of handling characteristics.
* the rolling diameter of any tyre fitted to a passenger car must not be more than 15mm larger or 26mm smaller than that of any tyre designated by the veicle manufacturer.
* note: 4x4 must not be more than 50mm larger or 26mm smaller than that of any tyre designated by the vehicle manufacturer.

so me having 20's on my 16" stock S15 is 52mm larger than the manufacturers crap...
ie. stock = 205 55 16"... i have 235 30 20"... that fails by 2x...

there is a formula, i have the sheet the cops gave me so if you want it give us a yell...

i would say, 2" above is about right, depending on the tyre specs tho