[Mr V]

What type of motors and how are you using them? How are you determining that they are overheated? When you say after the wheels stop moving do you mean after you cut power to the motor or are you still powering the motor and stalling it?

It is normal for the temp of a motor to continue to rise after it has been stopped. This is often referred to as heat soak. The majority of the heat a motor generates is in the rotor due to the resistance of the windings. It takes time for the heat in the rotor to transfer to the case which is why the external temp will rise for a period after shut down.