You are recommended to fit the new tires (or the least worn) on the rear axle of your vehicle, whether it is a front or rear, 2 or 4 wheel drive.
This ensures better control and handling in situations of emergency braking or on tight bends, particularly on wet surfaces. The loss of rear wheel grip is not easy to be controlled by the driver. On a bend, this means that the car oversteers and the rear of the vehicle starts to skid. Drivers are tempted to brake and turn the wheel too hard... and they end up going into a spin! Only an experienced driver would have the reflex to do the opposite, namely countersteer and accelerate.
Loss of front wheel grip (understeering) is easier to correct with the steering wheel, whilst taking your foot off the accelerator. Fitting the best tires at the rear, the driver enjoys a substantial gain in safety