A shake that starts around 55 mph is usually a tire or wheel. One that changes with braking or acceleration is not. How the speed and feel narrow it down.
A vibration that appears at highway speed and smooths out above or below it is one of the most common complaints on the South Plains, where most drives include a stretch at 70 mph. The cause is usually a tire or a wheel. But not always, and where you feel the shake, when it appears, and what changes it narrows the list quickly before anything is taken apart.
Where you feel it
- Steering wheel. A front tire or wheel problem. The steering wheel shakes side to side in your hands.
- Seat and floor. A rear tire or wheel problem, or something in the driveline. You feel it through the seat rather than the wheel.
- Whole vehicle, both wheel and seat: often more than one tire, or a driveshaft.
When it appears
- At a specific speed band, typically 55 to 70 mph, and smoother above and below: classic tire and wheel balance. The imbalance excites a resonance at that speed.
- Gets worse the faster you go without a smooth band above: often a bent wheel or a tire with a broken belt or a separation.
- Only when braking: rotor thickness variation, not a tire. Brake shudder covers it.
- Only under acceleration, easing off when you lift the throttle: driveline. A worn CV joint, a U-joint, or a driveshaft out of balance.
- After a tire service that was smooth before: a wheel not seated flat on the hub, a missing weight, or a lug torque problem. Go back to the shop that did it.
- After a pothole or a curb: a bent wheel or a damaged tire.
- Started suddenly on a muddy road: mud packed in the wheel. Wash it and see.
The tire and wheel causes
Imbalance is the common one, and it is fixed on the balancer. Wheel weights fall off, tires wear unevenly and lose their balance, and a tire that has sat for weeks develops a flat spot that sometimes works out and sometimes does not. Why balancing matters has the detail.
A bent wheel shows on the balancer as a wobble and cannot be balanced out. Steel wheels bend at the lip on potholes; alloys crack. A separated or out-of-round tire feels like a bent wheel and shows up as a bulge in the tread or sidewall, or as a tire that hops on the balancer. It is finished and it is dangerous at speed. Uneven wear, especially cupping from worn shocks, makes a tire vibrate no matter how it is balanced, and the fix is shocks and then tires.
The other causes
- Worn wheel bearing. Usually a hum that rises with speed rather than a shake, but a badly worn one lets the wheel wobble. Wheel bearing noise sorts the hum from the tire.
- Worn ball joint, tie rod or control arm bushing. Lets the wheel move, which shows as a shake that comes and goes and a vague steering feel.
- Driveshaft or CV joint. Speed-related but tied to acceleration, and felt through the floor.
- Brake caliper dragging. A rotor heated by a dragging pad warps and shakes, sometimes without braking.
- Engine or transmission mounts. Rarely, a shake that is really an engine vibration reaching the body at a certain load.
How we find it
- 1A road test to feel where and when it happens.
- 2Every wheel on the balancer, which also shows a bent wheel or an out-of-round tire immediately.
- 3Tires inspected for bulges, separations and wear pattern.
- 4Hub faces checked for rust and debris, lug torque checked.
- 5Suspension and steering checked for play.
- 6Driveline joints checked if the shake follows the throttle.
Most highway shakes end at step two. The ones that do not get the rest of the list rather than a guess.
Frequently asked questions
Can a balance fix a shake from a bent wheel?
No. A bent wheel is out of round and no amount of weight corrects that. The wheel is straightened or replaced.
Is it safe to drive with a highway vibration?
A mild, steady balance shake is safe to drive to the shop. A growing shake or one with a visible tire bulge is not.
Why is it smooth at 75 but shakes at 62?
The imbalance excites the suspension at its resonant speed and passes through it above that. It is still there at 75; you just cannot feel it as much.
Balancer, lift and the road test at 13209 Frankford Ave, Suite 29, Lubbock, TX 79424. Tire repair and replacement if that is what it turns out to be. Call (806) 458-2709. Drivers make the trip in from Floydada and across the South Plains for it.
Need this handled today?
Bring it to the shop.
Tire, brake and full auto repair at 13209 Frankford Ave, Suite 29, Lubbock, TX 79424 — serving drivers from Lubbock, Wolfforth, Shallowater, Slaton, Idalou and the surrounding South Plains.