I have inherited a well established overgrown grape vine (2 big trunks), in my new backyard. I have no idea how to care for them, as they were let grow themselves into a tangled piled up knot, seven feet high! They produced about ten bunches of very dark purple/black fruit last September (birds got them!). I am thinking of radically pruning everything away down to the two trunks (about as thick as my wrist), and starting fresh with a new trellis and wires.

Any advice?

Thanks,
Gala

For a mess like that I think you have the right plan. You will miss fruit next year but will have a full crop in 2015.

You could try to do the pruning over two years and still have fruit this summer. But it's not so simple to leave some one year wood for fruit and still remove most of the older wood. It's possible if there is some one year wood that arises near the head of the trunks.