Hello to all. I have a 1999 GT vert. Last year I swapped out the stock 17" rims for 18"x9" Saleens and I put Toyo 255x45x18 on them. Since I did this I have had a front end shimmy problem ever since. The problem lies between 45 and 60 mph. Tires have been replaced by Toyo once they have been balenced 4 times between the 2 sets. They have been rotated twice. Rims have been checked twice by two different people. The front end has been checked two times by different people. I have read in different forums that this not an uncommon problem and the problem lies with the lower control arms bushings being too soft from factory. Is this true? What do you think? Any suggestions? Thank you for your time.

By the way, this can is a pampered car. Run about 1000 miles per year, garage kept and I drive it gentley.