what cause the car to vibrate when riding down the road

have your tires checked for shifted belts. Roy

Your tire pressure could be off or you probably need an alignment

Try having the tires balanced or jack up the car spin the wheels see if they spin "true" get the tires that spin the most "true" on the front of the car and have them balanced. If the tires are balanced and you still have a problem check for worn suspension bushings or damaged or worn steering components.