One rear tyre is the original, the other has had 2 punctures, and when the second one occured it was too close to the first one, so the tyre was replaced, but still loads of tread on the original, I reckon it will get to 60k no problem.
I leave the same tyres on all year, so no swapping for winter rubber.
I feel they could have lasted a bit longer had they not worn excessively on the inside edge, despite having the tracking checked when the new tyres were fitted (July 2012) and at the two punctures (Oct and Nov 2012), it just appears learners driving style eats tyres ! Nothing new there.