I have a 2008 GS 350, very good car. I previously had Falken tires on the car that did well, however these tires were coming to an end and i went to Good Year and purchased 4 Assurance comfortred touring tires 70K, had my car aligned etc. when I got in my car and began driving, I felt heavy vibration in the front which i never felt before with the Falken tires. I drove it for another 30mins and took it back and told them the something isn't right. They look at the wheels and realized the weights were unbalanced. So they went back and tried to balance the weights on the wheels, we then took it for a test drive and it did a lot better, but I still could feel a little vibration in the tires. I told Good Year I will test drive for a day and if it continues I will bring it back. What could possibly be my problem, now that I have new tires on the car? Could the weights need to be balanced some more. You can really feel it when I slow down to about 35-40 miles.

 

Bad tire / tires... There is always a chance that one of the tires has excess runout causing your issue... It can be diagnosed by using a Hunter 9700 series Road Force balancer very easily, Also, a good technician can usually do a pretty good job of the same by watching a tire spin on the balancer as well...