Had a slow puncture in one of my rear 265 35 20 GY F1 A2's.   Whilst off the rim I asked them to measure the tread: 4.75mm at the outer grooves. 4.5mm centre. Mileage 19,000.   So, a bit more wear to go on these. 25k miles down to 3mm would be acceptable.   How have your Goodyears or "other" brand tyres faired, and what type of driver are you? I'm not an aggressive driver and the car is my daily, 12k miles a year.