Knowing your approach, departure angles are important factors to take into consideration when off-roading as it alone is what allows you to traverse over obstacles without damaging your vehicle.
When determining the Approach angle (A in Diagram) you must imagine a flat line running underneath your front wheel to the rear wheel this is your ground line and for your approach angle, it starts at the base of your front wheel. Now draw a line from the most forward, the bottom part of your bumper to the ground line starting at the base of your wheel. Where those two lines meet determines your approach angle. Now imagine an obstacle and your front bumper is hitting a said obstacle, this means that your approach angle isn’t large enough to clear this particular obstacle.
Your front end is over the obstacle. now you need to get the rest of the vehicle over as well. Now you need to know your vehicle’s Break-over angle. How do you determine this? You start at the base of both your wheels and draw a line to the lowest point in the centre of your vehicle, usually the transfer case or the muffler in off-road vehicles. From the lowest point draw a line to the highest part of the chassis in the centre of the vehicle and you will find it forms a corner (see B in Diagram) and that is your Break-over angle. It is important to know this angle because you’ll then know where your vehicles lowest point is and thus allowing you to be cautious of it when off-roading.
Finding your vehicles Departure angle is very similar to finding the Approach angle. You run a line from the base of your wheel to the lowest point of your rear bumper this line and the ground line will form a Departure angle see (see D in the diagram). However you’ll find that your departure angle is much worse than the approach angle, there is nothing wrong with that, it’s just how most vehicles are designed just also remember that a tow bar will decrease your Departure angle so if possible detach it before going off-roading.
Why are these angles important?
These angles help you to determine your vehicles true limits. If an obstacle’s height is greater than the angle you won’t get over it without damage. Knowing your vehicles Approach-, Break-over- and Departure angles will also help you better understand what modifications to get and how they will benefit you, like for example a replacement front bumper to increase your Approach angle. Or bigger tyres to increase ride height to help better the vehicles Break-over angle. It allows you to know the limits of your vehicle as well as how to increase those limits to make it a better off-roader and overlander.