The space margin depends on light and weather conditions as well as terrain (road curvature, hills, trees or other obstacles).
The time margin depends on the space margin, your reaction time, and your speed of travel.
You may appear to have a lot of time or space in icy conditions, but that can be an illusion. A collision course on ice will result in a collision, regardless of the time or distance involved.
Insufficient information is provided to be more specific.