Why is my car shaking when I drive?

Start with when it shakes

The cause usually shows itself in when the shake happens. A shake in the steering wheel at highway speed is most often a tire or wheel problem. A shake only under braking points to the brakes. A shudder at idle or under load, especially with a check engine light, points to the engine. A throb you feel in the seat more than the wheel often points to the driveline.

Tires and wheels

This is the most common cause. GM's service guidance calls a shake at highway speed on smooth roads the most common tire-related ride complaint, and says it can come from imbalance, a tire that is out of round, or tire force variation.^[1] A perfectly balanced tire and wheel can still be oval shaped and cause a vibration.^[1]

That is why a shop starts with balancing, which is the simplest of the three to correct, and then checks roundness if the shake remains.^[1] Volvo's guidance adds that too-high tire pressure makes a car harsher and adds vibration, so pressure is worth checking first.^[2]

Damage matters too. Virginia's inspection rules reject a tire with knots or bulges in its sidewalls, a broken belt under the tread, or tread separating from the fabric.^[3] They also reject rims or wheels that are bent, cracked or damaged so as to affect safe operation.^[3] A pothole strike can cause either one.

Flat spots after the car sat

If the car has been parked for hours, the tires can hold a temporary flat spot. GM's guidance says this kind of vibration can come and go during the first 10 minutes of driving above 45 mph, and that if it continues after that, a flat spot is ruled out.^[1] So drive for a while before you decide.

Brakes

If light braking makes a steering-wheel pulsation worse, GM treats it as brake-induced pulsation, a brake problem rather than a tire problem.^[1] Brake work is a safety item, so do not put it off.

Driveline

A low boom or throbbing that you feel in the seat more than in the steering wheel points to the driveline, which can be out of balance or misaligned.^[1] Volvo's guidance says vibrations are usually caused by the driveline, especially on all-wheel-drive cars, or by the wheels.^[2] This needs a shop with a lift.

Engine misfire

A shake at idle, or a stumble when you accelerate, can mean one cylinder is not firing properly. Worn spark plugs and a weak ignition coil are common causes. If the check engine light is on, FuelEconomy.gov says to have the vehicle inspected by a mechanic.^[4] A flashing light means ease off and get it looked at promptly. The stored code tells the shop where to start, and our answer on why the check engine light comes on explains what to expect.

What you can check yourself

Set each tire to the pressure on the driver's door jamb sticker, not the number printed on the sidewall.^[4] Then look for bulges, uneven wear, a nail in the tread, a bent rim or a missing wheel weight. These checks need no tools beyond a gauge, and they give the shop a head start.

Stop and call a pro if

• The shake is severe, or started suddenly after a bump or pothole.
• The check engine light is flashing.
• You see a bulge in a tire, or a wheel looks bent or loose.
• The brake pedal pulses, the car pulls to one side, or you hear grinding.
• You smell burning or see smoke, or the oil pressure or temperature warning is on. Stop driving.

Do not jack the car up or loosen wheel parts to chase a shake. Balancing, alignment, brake and driveline work all need a shop's equipment.

What to tell the shop

Give the speed range, where you feel it, and whether braking changes it. Ask for the trouble codes if a light is on, and for a written estimate before work starts. For what a diagnosis costs, see how much a car diagnostic test costs in Virginia. If you are weighing where to take the car, read dealer or independent shop for engine diagnostics.

Browse more automotive repair answers or see local automotive repair businesses. When you are ready, describe the shake once and local shops will quote the diagnosis.