When should you not turn on the front wheel drive of an agricultural tractor?

Driving on a hard surface with four-wheel drive engaged leads to the build-up of harmful stresses in the drivetrain and causes excessive and uneven tyre wear. This is because when turning, the wheels on the front and rear axles rotate at different speeds, and the hard surface prevents compensatory slip. Therefore, on a paved road, four-wheel drive should only be engaged when necessary to overcome a temporary, high resistance.