Car & Driving Vocabulary
Approach: The angle measured by drawing a straight line from the front of the front tire to the bottom of the front bumper. This angle is how steep a hill the vehicle can ascend without hitting or scraping the front bumper. Read this article.
Departure Angle: The angle measured by drawing a straight line from the back of the rear tire to the bottom of the rear bumper. This amount is how steep of a hill the vehicle can descend without scraping the bumper. Read this article.
Ground Clearance: The measurement from the ground to the lowest point on the underside of the vehicle. This amount is how much clearance the vehicle has without scraping the underside of the vehicle. Read this article.
Axel Ratio: This number is a ratio of the size of gears, so a 2:1 ratio gear has a gear turning the axel that is twice the size of the input gear. The axel ratio translates basically to how hard your motor has to work, so in essence it means power and torque.
The larger the number, the more power you have for climbing hills or towing a trailer, but it reduces your top speed and fuel economy. This is because the engine must turn at a higher rpm. A higher number is ideal for severe off road, because it gives you more power and torque, and you don’t cruise at a high speed anyway.
For example, if you plan on highway driving mostly, with some moderate off road or towing, then you would want a number in the middle, to satisfy both needs, so around a 3:1 or so. If you are planning on lifting your SUV and putting bigger tires on it, then a lower ratio (higher number like 4:1) would be ideal. You would then have the power you need to turn those bigger tires.