Why not just tax the tires? Seems like they are good indicator on how much you are using roads and how many miles you drove etc.
(Safety maybe an argument. Don't do it so people don't drive on shitty old ones)
The downside is that it would penalize soft rubber as well as the usage of winter tires.
Now most people only replace them at the milage limit like their oil because they run out their miles faster but for some people (like me) I tend to replace things on time more often because I do not drive that much
It also depends on the make and where you live. I stretched my Yokohama's out to ~80k miles with good tread still left when I replaced them. But I live in the southern part of the US, so we don't have to deal with snow and ice cycles that cause tires to wear faster.