how much tyre tread is safe

In Australia, the legal minimum tyre tread depth is 1.5 mm—fine for avoiding a defect, not exactly the wet-weather hero you’re after.

For real-world safety, replace at around 3 mm (closer to 4 mm if it buckets down where you drive), because braking distances grow uglier as the grooves vanish.

Use a proper tread gauge and check across the full width and around the tyre; wear never distributes itself like a polite dinner guest.

If you’re flirting with the wear bars, you’ve already left it late—those tyres are basically slicks in denial. Consult official documentation for exact figures.