Isn't it simpler to just have weight categories and base the tax on that?

Weight category multiplied by a yearly mileage reading (MOT or declared for first 3 years and corroborated at it's first MOT so you can't lie)

Seems safer than people risking it on a set of overly worn tyres to avoid paying. I also envisage tyre theft becoming a problem there too. Also very unfair if an unlucky driver who only does 3000 miles a year and just has brand new tyres who unfortunately runs over some debris causing a failure.

This is the take. People seem to treat everything like it's a sport and pick a team early on and stick with it vehemently.