Am using AT3 on MY11 4.4TDV8
Front left has 4mm
Front right has 5mm
Rear right 6mm
Rear left 5mm

At what point do folk change their tyres?

I was going to change the front pair for AT3 again when the front left gets to 3mm
Or….
Change the whole set for Zeros with Noise cancelling when the front left gets to 3mm, or in October - whichever comes first

AT's are something I haven't run.....

For my regular summer Contis I swap at 3mm. For my winter Contis, 4mm.

What's the reason you bought AT's ? That should help inform you of when to change.

If you just like the look, then 3mm is good - or 1.6mm is the legal limit. If you're using them in mud, then you need a bit more tread depth for them to be effective etc..... If it's more for snow, then I'd be inclined to run them through the summer but change in the autumn - as above, winters need 4mm really.

4mm for road is my personal limit. 3mm is generaly the limit before wet braking performance starts to rapidly decline. Age related rubber deterioration can be a reason to change them if you don't do many miles. I would personaly change AT3's or any AT tyre for a road tyre even if it was brand new as I concider wet braking to be a priority quality in a tyre but each to their own...... 2012 TDV8 Vogue (L322)