The main reason to buy a roof bar is that it is the most practical, safe and secure method of extending the load carrying capacity of your car. With a few simple attachments a pair of roof bars can be used to carry all manner of equipment such as ladders, planks and DIY kit or with some extra accessories to carry bikes, surf boards and skis. With the addition of a roof box you can increase load carrying space for items that can't be attached to the roof bar directly.

The first thing you need before you can carry anything on the roof of your car is a pair of roof bars and you should bear the following in mind when using a set of roof bars.

1. Don't overload your roof bars; most roof bars are designed to carrying lightweight objects like skis, small ladders, well-secured aerodynamic cargo containers (like those offered by Thule) and other light loads.

2. Watch out for driving with a higher centre of gravity; by putting heavy loads on your roof you will raise the centre of gravity of your vehicle, which could increase the chances of a causing your car to roll during emergency maneuvering or in the event of an accident.

3. Strap loads down properly; cargo improperly secured to a pair of roof bars can fly off and strike vehicles travelling behind you, sometimes with tragic results.

4. Remove roof bars when not in use; cars are designed to be aerodynamic and a roof rack causes increased drag and this makes your fuel consumption rise considerably. Reduce fuel consumption by removing your roof bar when not in use.

5. Always read the manufacturers guidelines; each set of roof bars is constructed differently and the only way to ensure that you are using them safely is to make sure you fully understand you particular set of roof bars so read the supplied instructions carefully.