I just got back from Firestone to have my alignment checked. My symptoms were slight pulling to the right and wandering, mostly noticeable on the highway. They did a full check and said that I was within spec all around except the right rear, which was 0.1º out of range. They checked with Lexus and found the only fix was to change the lower radius arm to one of a different length. The factory only sells them by length, not the degree of change it will correct. And at $255 per plus labor, I didn't want to waste my $$$.
So, am being fed a load by Firestone or is this problem/solution experienced by all Lexus owners?

BTW, I have less than 1k miles on a new set of Michelins form Costco.

 

Yes, I have heard of that rear alignment issue and ostensible "fix." Personally, I would not rely on Firestone's alignment / measurement tools for the LS. The top high-end wheel alignment systems are expensive and need precise, periodic calibration - otherwise they give incorrect wheel measurements. I would have a Lexus dealer do the wheel alignment.

Also, depending upon your front-end wear, it's more likely worn suspension parts are causing wandering. Remember, the wheel alignment is done on a stationary vehicle, but the steering (front wheels) is while the car is moving, and subject to road impacts, street grade variation, crown in road, etc. A knowledgeable technician can set the alignment perfectly, but if the suspension is worn at critical points, the steering will wander. One obvious check you can do, be sure air pressure is correct in all 4 tires.

 

I also noticed that wandering was more of an issue with the tires over inflated. I initially was going to 36 or so psi. Going back down to 33 helps the car feel more planted. Kind of odd how just a few pounds can affect this. Also, check you LCA's for leaking bushes. There is a big fat liquid filled bushing that is pretty easy to order and fix in the front. It seems to be the most common.

 

Rear suspension links are non adjustable. The only way to make adjustments is by replacing with different length arms sold by Toyota/Lexus. Your other option is to go aftermarket and buy adjustable arms. I would do the later as it will give you the ability to fine tune vs. fixed position correction.