Understeer is a phenomenon experienced when cars go around corners and the front tires lose traction, causing the car to go wide around the curve. There are a number of conditions involved in understeering, and it can be corrected to bring the car back on course. Many cars are designed to have a tendency to understeer, as it is believed to be easier to control than oversteer, where the rear tires lose traction and the car may spin out of control.
The aerodynamics of a vehicle are an important factor in how frequently it understeers, as a design that puts weight in front will help maintain traction on the front tires. The suspension can also be an issue, as can conditions on the road; if a road is icy, muddy, snowy, or otherwise slick, it is harder to maintain traction when moving around curves. Drivers can also engage in behaviors making understeer more or less likely, such as taking a turn too fast or braking hard while going around a turn.
Drivers can recognize understeer when it happens, as the vehicle will start drifting wide, almost like it is being pushed, and it will not respond to the driver's turn of the wheel. Yanking the wheel hard over is not recommended. Instead, drivers should take the foot off the gas and brake gently to slow the car down and bring it back under control. Drivers who experience this problem frequently may need to adjust their driving habits, taking curves more slowly and avoiding sharp braking while moving into turns, and the car can also be evaluated to see if an issue like poor tire inflation or badly tuned suspension is causing understeering.
This problem can be a big problem on the race track, where drivers are moving at very high speed in a limited environment with numerous other cars. If racers start to understeer around a turn, they can drift into other vehicles and cause an accident. Race cars are precisely designed for speed and issues like understeering are considered in their engineering, with designers taking steps to make this problem less likely, such as distributing weight across the body of the car to help it maintain traction.
In driver safety courses, drivers may be offered an opportunity to simulate dangerous driving conditions on a closed course so they can learn how to get a vehicle back under control. These courses can also familiarize drivers with the early warning signs of a safety issue, allowing them to take action before a problem like understeer develops.