How do I convert all strings in a list of lists to integers?

I have a tuple of tuples containing strings:

T1 = (('13', '17', '18', '21', '32'),
      ('07', '11', '13', '14', '28'),
      ('01', '05', '06', '08', '15', '16'))

I want to convert all the string elements into integers and put them back into a list of lists:

T2 = [[13, 17, 18, 21, 32],
      [7, 11, 13, 14, 28],
      [1, 5, 6, 8, 15, 16]]