What Causes a Car to Sway Left and Right When Driving at High Speeds?
2 Answers
There are several reasons why a car may sway left and right when driving at high speeds: 1. Tire issues: First, if the tires are new, performing a wheel balance and then checking for swaying can completely rule out tire problems. If the tires are old, even after performing a wheel balance, significant tire deformation or uneven wear could still cause swaying. This is because wheel balancing is adjusted using lead weights, and if the wear is uneven in the middle, a wheel balance alone won't solve the issue. 2. Incorrect four-wheel alignment: This problem is more common in older cars. The description mentions swaying, not shaking. If the issue is shaking, the suspension system, tie rods, and front wheel toe must be checked. If it's swaying, the suspension, tire pressure, and front wheel bearings should be inspected. After inspection, a four-wheel alignment must be performed.
I have over 20 years of driving experience, and every time the car body sways left and right on bumpy highways, it makes me so nervous that my palms sweat. The common causes of this issue are uneven tire pressure—higher pressure on one side and lower on the other—or inconsistent tire wear, especially noticeable on aged tires. Suspension system problems should not be overlooked either, such as leaking shock absorbers or loose connecting rods, which can lead to uncontrolled body sway on rough roads. Loose chassis fasteners can also worsen the wobbling. For example, last time I was driving on a mountain road, a loose chassis screw caused the car to bounce like a trampoline. I recommend checking tire pressure before trips to ensure balance and scheduling regular wheel alignment and dynamic balancing tests as preventive measures. If the car starts swaying on the highway, slow down immediately, pull over, and check the tires. Safety comes first—don’t hesitate to spend on repairs to avoid major accidents.
