New tyre tread depth 7mm Now 2mm Legal limit 1.6mm Wear = 5mm Remaining tread = 2 - 1.6 = 0.4mm
Remaining life = 0.4 x 9125 / 5 = 730 miles. So total miles will be 9855.
But as others have pointed out it hasn't been "safe" for some time. For wet weather 3mm is considered about the limit.
How do you manage to get by with no basic maths skills?