

An EU directive has no effect in Italy unless a law that acknowledges it is enacted. True, we must write a law that implement the directive but it is not an automatism.
This is exactly what I wrote in the comment you replied to, albeit with different wording? Basically the only other options if the nation does not want to comply is: a) suffering punitive actions from the EU indefinitely or until they comply or b) leaving the EU.
Double checking and it doesn’t seem like it? Then again I don’t live in Italy. Here in Sweden you’ll face a fine of ~2000kr (roughly 200€) per tire on your vehicle that is out of spec.
https://www.europe-consommateurs.eu/en/travelling-motor-vehicles/motor-vehicles/winter-tyres-in-europe.html
…and thus it is much simpler to handle these kinds of regulations at a lower level. No need for everyone everywhere to agree, people can have rules that work for them where they live, folks are happier and don’t have to struggle against a system run by bureaucrats so far away they have no idea what reality on the ground is (and they can’t, it’s impossible to account for every scenario centrally). Even on a municipal level certain regulations differ, and that’s completely ok!