Another industry standard is maximum load current is usually 3 times the maximum run current listed in the motor tag. If the tag says max run current is 5 amps then locked rotor current should be about 15 amps. You can test it yourself and see. Lock the shaft so it can not turn then turn on the motor with and amp clamp or amp meter in the circuit. Take a quick 5 second reading. These will tell you a lot about the design of the motor. Most good motors will be 3, some manufactures might be about 2.5 to 2.7, cheap Chinese motors are 2.