There are different reasons why your car might be shaking when you drive. One of the reasons for a bad ride is flat spots on your tires. Flat spots can be caused by locking up your brakes or by your car or truck being parked for a long period of time in one place. There are two ways to correct flat spots on your tires, depending on the cause.
Fill each tire to the maximum level as noted on the sidewall of the tire, using the air compressor. Check to make sure the pressure is correct using the tire gauge.
Drive the vehicle for at least 150 miles. If the flat spots were due to the vehicle being parked for a long time, this should solve the problem.
Release air from the tires to bring the tire pressure back within the normal range, as noted in the vehicle's owner's manual and on the driver's door information plaque. Do this by inserting a valve core tool into the tire stem.
Take the vehicle to a tire shop. Most dedicated tire shops have tire shaving machines that will shave the tyre's tread until the flat spot is gone. This is the only solution for a flat spot caused by a long skid.