Minimum legal tyre tread depth

Highway code stopping distance for 50mph is 53metres anyway, so even with 1.6mm you’re still well under the supposed stopping distance they expect, and have thus based all the speed limits, 2 second rules and so on around, don’t see the problem personally. Make everyone drive everywhere at 10kph, or not drive at all, walk instead, mind you that’s dangerous, what with kerbs, walls, lamposts and other things to hit.