NSW Legal tyres?

My understanding is one the fine indicator grooves wear out, you have to change the tyres.

Correct?

We've had a bit of scuffing on the inner fronts and swmbo was told by the nissan mech they were "poor", so now she wants to immediately change them.

I'm of the view that rotating them to the back will put full(un scuffed inner tread)_ on the front and give us a bit better mileage(kilometrige/distance) out of them before we replace them. The scuffed spent about 30Kkms on the front and 15Kkms on the rear(slack on rotations) and the fine indicator groves are still clear on the worn area.

Rotate them I say. Will give you a few more K's. If the indicators are still unworn then keep weeding then just drive cautiously in the wet.

The tyre has to shed water properly from the entire surface, so any point where the wear indicator has been reached on the tyre signals the end of legal life for that tyre.

Personally I wouldn't compromise on it: those 4 pieces of rubber are what helps keep my car where I want it to go (or stop) when I want it to.

Show them the price of the km2's you want, might help convince the rotation a touch for you