broken belt in the tire, uneven wear
On almost every car, the vibrations are caused by the tires,, you need to take it to a tire balance and aligment,, if that doesnt repair the simptom,, maybe a motor problem,, but that's a very extrange situation,,, good luck!! Jesus S.
Could be wheel balance.
out of balance
Normally this is caused by a tire out of balance or a bent wheel.
Normally tire out of balance or bent wheel.
You will feel the car vibrate around 50-80 MPH
an electric motor with an off-balance weight on its shaft.
Tire/wheel balance
It is possible that the tires are out of balance. Any reputable tire dealer can check the balance for you.
My guess would be that a small motor spins a disk which is slightly out of balance. If the wheel is perfectly balanced, the wheel would not vibrate. Instead, it might give off a whirring sound, but not vibrate. Out of balance, the wheel would have momentum in one direction and then another as the wheel spins. It may be interesting to see the actual mechanism.
Normally it is a tire out of balance. Can also be a bent wheel.
Tires and/or wheels may be out of balance