I recently foolishly bought a car sight-unseen from an Auckland dealer (I'm in Tauranga, had a friend pick it up and drive it to me, I did NOT instruct him to inspect the car as he was doing me a favour). Anyway, among the other issues that the lying prick of a dealer didn't disclose, three of the tires are right on the wear bars. The front right tires obviously didn't pass the WOF, so was replaced with a new one. So I have three heavily worn tires and one new tire. I've always understood that it's a safety hazard to have mismatching tires like this, particularly on the same axle.
Should the dealer not have replaced both front tires, at the very least? I mean, really he should have replaced them all because the car really isn't fit for purpose with barely-WOF-able tires, but that's another point.