4.8is Tire Sizes & hey from Australia

[davewatson]

Hey Guys,

I need some experienced opinions with regards to tire sizes.

I have an 06 4.8is, which to my understanding I can only get 18's onto as the smallest rim due to the brakes.

My aim at this stage is to use the car on Fraser Island (which to those who don't know is the worlds largest sand island) - So i want the smallest rim, most rubber I can get..

I have read mixed reports about upping rubber - I have read people who have fitted 275/60/18's without issues, but can't find this size tire available.

I know fairly confidently that 255/55/18 will fit, but would like to go bigger so that I can lower the pressure and balloon out the tires as much as possible.

Any advice would be great on what people have without rubbing etc, would be great!

Thanks guys!

Oh and some pics of my new car