Rims & Tires

I replaced my CLK 17 rims and tires with 18 inches earlier this year, but since then I have gotten a lot of vibration over sixty. My dealer tells me all four tires are out of round. They can swap my stock 17s for more sportier Benz 17s. Is this a good idea and does anyone have any suggestions. I need to lose the vibration or the the car. It is annoying.

Thanks