THE TWO-SECOND RULE...
Under normal conditions, the two second rule is an easy way to make sure you have allowed enough following distance between your vehicle and the vehicle in front, no matter what speed you're traveling at.
TO CHECK IF YOU ARE TRAVELING TWO SECONDS BEHIND THE VEHICLE IN FRONT...
Watch the vehicle in front of you pass a landmark - such as a sign, tree or power pole - at the side of the road.
As it passes the landmark, start counting "one thousand and one, one thousand and two".
If you pass the landmark before you finish saying those eight words, you are following too closely - slow down, pick another landmark and repeat the words to make sure you have increased your following distance.
THE FOUR-SECOND RULE..
In bad weather, when the road is wet or slippery, or when you're towing a trailer, you need to increase your following distance to four seconds, because you'll take longer to stop if you need to.
To check that you are travelling four seconds behind the vehicle in front, follow the instructions above for the two second rule, but count "one thousand and one, one thousand and two, one thousand and three, one thousand and four" instead.
If you're following another vehicle and you don't intend to overtake them, you must leave enough space in front of your vehicle for vehicles to pass you.