I managed 7,000 before I just couldn't take it any more.
I had to "reprofile" the front tyre with a rasp to make it rideable. (approx 4,000 miles)
Both tyres were still legal when replaced.
Front was at 2mm tread at the lowest point and 5mm at the deepest.
Rear was at 2mm and 4mm.
Went PR2 and never looked back.
Will never buy Bridgestone again,.. unless the press reports that they have a PR3 beater.