This is what is listed under "Ground Speeds" in your tractor's manual:
Ground Speeds
NOTE: All ground speed calculations shown are with machine equipped with standard tires and operated at 2600 engine rpm.
Forward and Reverse - Range High 0-20.9 km/h (0-13.0 mph)
Forward and Reverse - Range Low 0-7.2 km/h (0-4.5 mph)
Make note that the speeds will depend upon your tires.