Tires
The only thing touching the road. Size is printed on the sidewall.
Signs it's worn: Tread under 4/32", cracks, bulges, vibration.
What's wrong with my car? · Tires & driveline
Car shakes at highway speed?
Usually: Tires out of balance, or driveline wear.
Shaking that grows with speed is most often a tire out of balance (a cheap fix at any tire shop). On rear- or all-wheel drive cars, worn U-joints or a driveshaft do it too.
The parts that fix it
Driveshaft
The long spinning tube between gearbox and rear axle on rear- and all-wheel-drive cars.
Signs it's worn: Vibration that grows with speed, clunk when you pull away.
U-joints
The flexible joints on each end of the driveshaft.
Signs it's worn: Squeak going slow, clunk from under the car.
See what these parts really cost for your car. Enter your VIN and we'll bring back 2-3 options from real sellers (dealer, name brand and budget), shipped to your door. Finding prices is free.
This is a first read from the symptom, not a diagnosis of your car. If you're not sure, have a mechanic confirm before you buy, and bring the prices you found here with you.