a = ['285/30/18',
'285/30/19',
'235/40/17',
'315/25/19',
'275/30/19']
print sorted(a, key=lambda x:x[-2:] + x[4:6] + x[:3])
YSA9IFsnMjg1LzMwLzE4JywKICcyODUvMzAvMTknLAogJzIzNS80MC8xNycsCiAnMzE1LzI1LzE5JywKICcyNzUvMzAvMTknXQpwcmludCBzb3J0ZWQoYSwga2V5PWxhbWJkYSB4OnhbLTI6XSArIHhbNDo2XSArIHhbOjNdKQ==