matplotlib strings as labels on x axis

Use the xticks command.

import matplotlib.pyplot as plt

t11 = ['00', '01', '02', '03', '04', '05', '10', '11', '12', '13', '14', '15',
       '20', '21', '22', '23', '24', '25', '30', '31', '32', '33', '34', '35',
       '40', '41', '42', '43', '44', '45', '50', '51', '52', '53', '54', '55']

t12 = [173, 135, 141, 148, 140, 149, 152, 178, 135, 96, 109, 164, 137, 152,
       172, 149, 93, 78, 116, 81, 149, 202, 172, 99, 134, 85, 104, 172, 177,
       150, 130, 131, 111, 99, 143, 194]


plt.bar(range(len(t12)), t12, align='center')
plt.xticks(range(len(t11)), t11, size="small")
plt.show()