I wanted to give an update on my tire balance issues: Yokohama gave me a credit on the Parada's and I replaced them with Michelin Latitiude (265/50R20) and guess what...same shimmy in the steering and the base of the car. So, after spending $1,200 on new tires did not correct the issue. Here's the run down on what I've done:
1. 2 set of Parada's (several balances, including force balance)
2. Took the car back several times to the dealer, which they finally took a brand new set of tires / rims from an '09 FX35 and installed them on my FX. I drove it for about 10 minutes on the expressway and the shimmy was gone. Dealer also stated that the hubs were not the issue.
3. Replaced brakes & rotors, which I still get a shimmy from hitting the brakes :-(
4. Replaced Parada's with the Michelin Latititude, with a force balance.
Big O, which installed the Michelin's, verified that the rims were not bend and that the force balance showed no imperfections in the rims/tires.
This is insane and is driving me crazy. Any speed after around 55-60 gives the shakes...both the base and steering wheel. The wierd thing is that different times the shake is not consistant in the steering. It wouldn't be so bad driving city, but driving hwy is aweful. So, it looks like the Parada's were a good fit for the car after all.