vibration annoying to the dangerous point. dealers can't find cause after 3 new sets of tires and 2 sets of rims. Road force balance indicates bad tires, but problem is in car. Can feel it in feet, butt, and hands on steering wheel. Many complaints all over internet... Why won't Buick admit to it and either fix the problem or recall their lemons. I have 2 2003s now, 1 base model with prestige package and 1 ultra both with 30000 mi... they have identical vibrations. I have owned 3 older parks and never had any problems, now I have 2 that I can't live with.