I have a '92 740 wagon w/ 97k miles. Yesterday, I had a local tire store put my summer tires on. I watched them, and I know that all went smoothly: they put the car on the lift and switched the tires. Simple. However, immediately on driving away I noticed a knocking sound coming from the left rear suspension. It is most noticeable at lower speeds (below 25 mph) over uneven/unsmooth pavement surfaces. I can also hear it faintly when I bounce the rear end up and down. Also, I can feel a corresponding "click" if I hold the left rear tire while someone else bonces the car. The only cause I can identify might be that something happened as a result of unweighting the suspension on the hydraulic lift. Any help/suggestions about the possible cause and solutions would be greatly appreciated.