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Oversteer and understeer explained

When you’re researching your next car, you might decide to read a lot of reviews. Here at carwow, we read more than most to build our famed aggregated car reviews – critics and road testers are a fantastic source to pass judgement on a new car but many fail to do so without descending into a maze of terminology.

Understeer and oversteer are two such arcane terms used by the reviewers. These terms describe how it handles when you push it beyond the limit of tyre grip.

It’s worth remembering, people who drive more slowly won’t fall victim to over- or understeer and, on modern cars, there’s a raft of safety equipment to make absolutely sure the below eventualities don’t happen. Still confused? Let us help…

Understeer – what is it?

This is when the car’s front wheels lose grip through a corner due to excessive speed. This causes the front end to push towards the outside of the corner and for the steering to become useless.

Understeer – what causes it?

Understeer occurs when the front tyres start slipping. This happens when the front tyres are asked to turn while also managing a lot of braking or speed. If you’re going rather fast or braking very hard and trying to turn the wheel, the extra momentum may cause the front tyres to slip in the direction you’re travelling so, instead of turning, the car ploughs straight on.

Understeer – how to stop it?

Slow down! Understeer almost always occurs when the driver is going too fast for the road conditions – but this can be as innocuous as doing 15mph around a damp mini-roundabout. Taking things a little slower will avoid most instances of understeer.

If you start understeering, you should start to reduce the amount you’re pressing the accelerator or brakes – don’t jump off them completely – and reduce the amount of steering angle you’re applying. Of course you might run out of road still, but this will increase your chances of getting control of the car back before that happens.

Oversteer – what is it?

Oversteer is an extremely similar set of circumstances to understeer, but affecting the back of the car. It’s the tendency in powerful rear-wheel driven cars for the back end to want to overtake the front during cornering. If you’ve ever seen an episode of Top Gear, the presenters rarely test a fast car without performing some sort of oversteer. Professional racing drivers are trained to hold the car in this state in the sport of drifting.

Oversteer – what causes it?

Oversteer normally occurs on cars that drive the rear wheels and happens when the car is turning and the driver applies more power than the tyres can deal with. This makes the tyres slip and try to push in the opposite direction to the turn, kicking the back end of the car out. The same effect can happen by braking too hard while turning or by suddenly removing your foot from the throttle.

Oversteer looks great on a racetrack or at a drift competition, as the rear of the car slithers about and billows tyre smoke into the stands, but it’s not as much fun on a public road as it usually foreshadows a very big accident.

Oversteer – how to stop it?

Much the same advice applies as for understeer – slow down! Power oversteer is often caused by the driver accelerating too soon in a corner so, if you’re at this stage, you need to reduce your speed. If you’re unlucky enough to get into an oversteer situation try to remember some basic tips – keep looking and steering in the direction you want to go and don’t suddenly jump off the accelerator or slam on the brakes. If you can, try to modulate the throttle to gradually bring yourself to a halt.

While all road cars are prone to understeer, in rear-wheel driven ones you will need to watch for oversteer too, so take particular care if you’re an inexperienced or not especially confident driver if you buy a car that drives the rear wheels. It should go without saying, don’t deactivate your traction or stability control unless you’re at a racetrack.

Other advice

In cold, rainy weather, a car’s willingness to oversteer or understeer is greatly increased because there’s less friction between tyre and road. This is even worse in the snow so always pay close attention to the weather conditions.

Since tyres are a significant component of the phenomenon, make sure yours are always at the appropriate pressure and sufficient tread depth to deal with surface water. If your car is started to display more oversteer or understeer than usual, check your tyres and also consider having the wheel alignment checked.

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