Stopping distances
The basic driving rule is - Be able to stop, on your own side of the road, in the distance that you can see to be clear!
...and on a single track road - Be able to stop in half the distance that you can see to be clear! (So that the other vehicle can stop too!)
Only a fool breaks the two second rule! This is the rule for a safe following distance (in DRY weather!) To test this, start saying the phrase as the car in front passes an object (e.g. a road bridge) and if you pass the same object before you finish the phrase - you're too close! DOUBLE this in the wet!