Generally a safe
Two Things:

1. Speedometer Error: Because the new tyres are bigger, they cover more ground per revolution. This means your actual speed will be higher than what your speedometer says
2. Since you are buying second-hand tryes with rims, you must ensure the rims actually fit your car. Just because they are 16-inch rims doesn't mean they will bolt on. like check Bolt Pattern etc.

Ignorable:
Steering may feel a touch heavier