I have '06 GS300 AWD w/the 18"wheels & run-flat tires from the GS430 since Feb. with 5500 miles. After about 2-3 weeks of purchase, I noticed the car seems to drift & require a lot of steering wheel correction to prevent the car from drifting out of my lane. Lexus corrected a slight steering wheel mis-alignment during the 5K maintenance & I had an alignment performed also, which seems to improve the tracking, but more times than not, the steering wheel & tracking of the car feels disconnected. The Lexus suspension drove the car & suggested the light feel of the steering wheel is normal & that the run-flat performance all-season tires that came with the 18" wheels may be contributing to the erratic tracking, because the rubber on the corners of the tires are harder than regular tire. He said, it takes time for the rubber to heat up, soften up, thus a smoother ride the longer you drive at a continuous pace vs stop & go traffic. Anyone else having this problem?