Understeer and oversteer, what exactly are they? "When you see the tree you're about to hit, that's understeer. When you feel the impact without seeing the tree, that's oversteer." That's how former rally champion Walter Röhrl explains it, simply and effectively. When a driving error causes the limit of grip to be exceeded, understeer and oversteer can occur: two abnormal, opposing behaviors. In both cases, the car ends up on a different trajectory than the one set by the driver.
When the front tires lose grip upon entering a curve, understeer is triggered. The car steers less than necessary and widens the trajectory set by the driver with the front end: instead of turning, it continues straight. Imagine the danger if the car points towards a wall at the roadside or towards the protective guardrail. Understeer primarily occurs because we are distracted at the wheel or want to drive beyond our technical capabilities. Why does it happen? Due to entering a curve too fast, a sudden turn, or sudden braking while turning, in low grip conditions.
When the rear tires lose grip during a turn, oversteer is triggered: the rear end widens the trajectory outwards, while the front wheels tend to tighten the curve's radius. The biggest risk in this case is ending up in a spin, perhaps with the car stopping in the middle of the opposite lane. Why does it happen? Due to sudden braking, sudden deceleration in a curve with a low gear, or a sudden turn while cornering.
"We verify this in our experience as instructors: in almost all cases, understeer and oversteer occur at a speed that represents the driver's limit, not the car's," comments Vito Popolizio. At the same speed, in the same situation, if the correct driving techniques are applied, the car does not lose grip. The technique for managing understeer is simpler than that required for controlling oversteer. For this reason, most recent cars are designed to have a tendency towards understeer.
In case of understeer and oversteer, abnormal and opposing behaviors, do we know how to intervene? What are the correct techniques, what errors to avoid, how to correct these dangerous phenomena? Does the weight on board change the vehicle's behavior? To find out more, consult our manual Sicuri al volante, availableon Amazon in print version and on Lulu in print version and as an ebook.
