Maximum baud rate speed of HardwareSerial

[Matsuo32]

Hi Is what maximum baud rate speed of HardwareSerial?, I need use 250000 , is it possible ? I try to set baud rate to 250000 and set D6 to LOW but i don't work.

 //UART
 //For hardware serial leave the communication settings on the module at default speed (9600bps) 
 Ch376msc(HardwareSerial, speed);//Select the serial port to which the module is connected and the desired speed(9600, 19200, 57600, 115200)