general problems of the 2006 Lexus GS430

Premature tire wear on 2006 Lexus Gs430. Inside shoulder of each tire prematurely wears in a "scalloping" fashion. Dealership is aware of the issue, says it is due to the sport suspension and it happens on all their "sporty" models. Dealership concedes that proper rotation, balance and alignment maintenance does not correct the issue. I was told by the dealership that 20,000 miles on any tire is what should be the expected tire life. Therefore there seems to be no correction for the failure offered, at anyone's expense. Primary safety risk is due to the location of the premature wear, which is not easily visible (inside shoulder of each tire). There are numerous bulletin boards online, including on the Lexusowners website, which confirm that this is a widespread issue with the engineering of the suspension on many Lexus models.