New tyres I have had usually start with 7 or 8mm. Are you measuring at the deepest point, in the centre ?

I can remember getting 50,000 miles out of a set of Michelin tyres many years ago (unfortunately no recollection of tread depth.) But 20,000 seems the norm these days.

I Usually get more that 7mm, possibly even 8mm in the centre on recent new tyres but usually a bit less at the edges. I you are measuring in the centre did you inadvertently measure down to a wear indicator bar?

I think less tyre life on modern cars has much more to do with the obsession with ultra low profile tyres. My poverty spec mk I 2001 Skoda Octavia had tall profile tyres (175/80 R14 88T) and it used to get over 45k miles out of a set. My current poverty spec 2014 Superb has 205/55 R16 tyres and easily got 35kmiles out of a set of Continentals and looking as though it'll get more out of a set of Michelin Crossclimates. A friend of mine with an Octavia vrs with much lower profile tyre was moaning that he struggled to get 15k miles out of a set!

[EDIT] - Until recently (thanks Covid!) I'd had a long commute for over 3 decades so picked my cars carefully and part of the decision was always tyre size / cost.

Edited by Big John on 28/07/2021 at 19:40

I can remember getting 50,000 miles out of a set of Michelin tyres many years ago (unfortunately no recollection of tread depth.) But 20,000 seems the norm these days.

The car you had many years ago might have been a rear-wheel drive, as my impression is that front tyres don't last as long on a front-wheel drive car.