Cadillac Repair: 1995 Cadillac Fleetwood Brougham vibration, cadillac fleetwood brougham, cadillac fleetwood

Question
Puchased the above mentioned vehicle and have an intermittent problem.  The problem is when driving on flat roads at speeds of 60+ mph I often times experience excessive vibrations with the car.  When I purchased the car, I took my rims from my 1994 fleetwood Brougham and put them on this 1995 car.  The rims are not aluminum but steel.  I have purchased brand new Cooper tires to replace the existing Cooper tires, had them balanced and car aligned.  The problem still exists.  I have taken the car to four dealerships and several mechanics and they cannot diagnose the problem.  As murphy law applies, 3 of the dealerships never did experience the vibration after several test drives.  One dealership actually did experience the vibration and suspected the tie rods, however, the other dealerships said the tie rods were fine.  Everyone seems to tell me that it is the tires.  The rear shocks have been replaced about three months ago.  I am at my end wits with this intermittent problem and any advise that you can provide would surely help.  Thank You Leah

Answer
Without driving the vehicle personally there is no way for me to make an accurate diagnosis.

However, I have run across tires that can cause a vibration and or a road noise effect.

The only way to see if it is the tires is to replace them with another brand.