developing your smart driving skills Slippery or sandy road surfaces, worn tires, and under‑ or over‑ inflated tires that don’t grab the road will reduce traction. Slow  down if you are on a poor road surface.  Inertia  — this is the tendency for moving objects — in this  case, you and your vehicle — to continue moving forward in a  straight line. When you brake, inertia tries to keep your vehicle  moving. When you go around a curve, inertia tries to keep you  going in a straight line. The faster you are going, the greater  the force of inertia.  Gravity  — this is the force that pulls everything towards earth.  It’s the reason your vehicle slows down going up a hill and  speeds up coming down. It’s important to remember this when  you’re going downhill because your vehicle will need a longer  distance to stop.  Centre of gravity  — this is the point around which all of an  object’s weight is balanced. The centre of gravity for any object  can change. For example, a tightrope walker may carry a pole to  lower the body’s centre of gravity and make it easier to balance. Most vehicles are built on the same principle — low enough  to the ground so they balance well on hills, curves and uneven  road surfaces. But some vehicles — for example, some sports  utility vehicles, pickup trucks and camper vans — have a higher  centre of gravity. Whenever the height of a vehicle or its load  rises, the centre of gravity also rises. A vehicle with a higher  centre of gravity is less stable on uneven road surfaces and is  more likely to tip over on a curve taken at higher speeds. You need to remember this if you are driving one of these types of vehicles. The blue car has a low  centre of gravity. On a  curve, the weight shifts  to one side but the car  remains stable. The truck,  with its large wheels, has  a much higher centre of  gravity. On a flat surface  it is stable, but when  the weight shifts on a  curve, the truck becomes  unstable and may roll.  70