It's also fairly easy to see direction of rotation as the motor slows to a stop, or you can simply feel which way the prop is blowing air. But as I said in first response, T-motors, if you insure the unmarked wires out flat, are wired to run in the opposite direction of the stock motors. (i.e. if the stock motor being replaced has red and yellow "crossed", the T-motor will connect with wires in order - and visa versa.)
You will need to swap any two wires on each of your motor connections, assuming they are all running backwards!
bumper