We have a 07 IS250 RWD with 18 inch wheels and at right or left max turning radius we get a clunking or jerking sensation from the front end. I took it in for the 5k oil change and service and asked the Fresno Lexus dealer to have the techs look at this problem. They told me that when they had it up on the lift they checked everthing out and all was as everything was suppose to be. They said they took another IS250 from the lot and drove it around and it did the same thing so it is alright. I just can't believe and engineer would design a steering system to do this.