Rick's Free Auto Repair Advice

What is understeer

Definition of Understeer

The Society of Automotive Engineers (SAE) defines understeer and oversteer as deviation from a constant-radius path at a constant speed with a constant steering wheel angle. So, in an understeer situation, the front tires will begin to lose grip before the rear tires. In other words, the vehicle experiences less turning than the driver intended because the front tires are losing grip on the road.

Example of how you might experience understeer

You travel at an appropriate speed and turn your


Understeer—turn right on wet road or with excessive speed or heavy braking and the vehicle continues to go straight

vehicle to the right to take a right turn. The front tires slip and the vehicle continues to travel straight. In effect, the front tires will lose their grip on the road BEFORE the rear tires lose grip. This generally happens more on FWD cars, especially if you add acceleration during the turn.

What causes understeer and loss of grip

FWD vehicles wear out the front tires faster than the rear. Front tire tread depth of 4/32” or less will cause the front tires to lose road grip before the rear tires. FWD vehicles typically wear the front tires twice as fast as the rear tires. If you don’t rotate your tires at the proper intervals, you’re wear out the two front tires twice as fast as the rear tires.

However, all wheel drive (AWD) vehicles wear out all four tires faster than the same tires on a FWD vehicle. Rear wheel drive (RWD) and part-time four wheel drive (4WD) vehicles tend to wear out the rear tires first.

• Water on the road that causes the tires to hydroplane. The front tire will lose grip and understeer before the rear tires.

• Understeer happens when you enter a turn with too much speed, causing the front tires to lose grip

• Understeer happens when you brake hard while turning, locking the front wheels and causing them to lose grip

How to correct understeer

•Reduce turning radius at steering wheel

• Ease off the throttle

©, 2018 Rick Muscoplat


Posted on by Rick Muscoplat


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