Understeer and Oversteer Definition: What Causes These Conditions?
When a vehicle understeers and oversteers, various forces occur due to the speed and steering behaviour, which influence the cornering behaviour. The legendary German rally driver Walter Röhrl summarised this in an entertaining way: 'If you see the tree you are driving into, you have understeer. If you only hear it, you have oversteer.'
As a long-time racing professional, he knows exactly what he's talking about. Both oversteer and understeer reduce cornering speed, cause deviation from the ideal racing line, and affect not only driving safety but also lap times.
Is Drifting Oversteer or Understeer?
Oversteer is when the rear of the vehicle swerves because the rear wheels lose grip. In drifting, this phenomenon is used deliberately to make cornering spectacular and to push the limits of physics. The multiple world rally champion Walter Röhrl also has a suitable explanation for this: 'Drifting is the art of keeping an unstable state stable.'
Oversteer can happen if you accelerate too much in the bend or take the bend at too high a speed. In most cases, other factors such as wet conditions, the road surface, the suspension settings, the vehicle’s weight distribution, and the rubber compound of the tyres also contribute to the extent to which your vehicle oversteers when cornering. In addition, vehicles with rear-wheel drive and a high load on the rear axle tend to oversteer more.
How to Correct Oversteer
Unless you are a professional drift driver, you should quickly bring a car in oversteer back under control. However, this correction requires a lot of practice and precise steering technique, because if you countersteer too much or react too late, the rear end can swerve out of control.
As soon as you realise your vehicle is in oversteer, take your foot off the accelerator and reduce your steering movement. Countersteer slightly, but avoid making abrupt movements with the steering wheel. If you notice the car is no longer turning, be ready to quickly steer back in the other direction to counter any pendulum effect.