2003 LEXUS GS430 Suspensionfront Problems

I OWN A 2003 LEXUS GS 430 VEHICLE. DURING THE TIME THAT I HAVE OWNED THIS VEHICLE, I CONTINUE TO EXPERIENCE VIBRATION AND BRAKE AND WHEEL WEAR ON THE FRONT END ASSEMBLY. THE DEALERSHIP HAS ALIGNED THE FRONT END AND CHANGED TIRES, BUT THE PROBLEM IS REPEATING. I BELIEVE THAT THE VEHICLE IS IMPROPERLY DESIGNED EITHER TO ACCEPT 17 IN. TIRES OR TO HANDLE A 4.3 LITER ENGINE. THE DEALERSHIP INSISTS THAT ALL YOU HAVE TO DO IS ROTATE TIRES EVERY 5,000 MILES AND THERE IS NO PROBLEM, BUT THIS IS NOT THE CASE. AS A RESULT OF THE RUN-OUT AND OUT OF BALANCE CONDITION IN THE FRONT END OF THE VEHICLE, THE BRAKING IS UNREPEATABLE, AND, I BELIEVE, CAUSES A SEVER SAFETY CONCERN. THE PROBLEM HAPPENS WITHIN 3,000 TO 4,000 MILES OF AN ALIGNMENT. I BELIEVE THAT THIS PROBLEM IS ENDEMIC TO LEXUS GS 430'S WITH 17 INCH TIRES...