have your tyres inspected for bubbles or being out of round, and make sure they're properly balanced. also check your lugnuts for tightness.

if you have aftermarket wheels, make sure the hubcentric rings are installed. many times installers wont realize you have hubcentric rings and they'll fall off the wheel duing the tyre change process... when the wheel is installed back on the hub, the wheel is not centered perfectly onto the hub, causing severe vibration. the hubcentric ring is a plastic or metal ring, that is inserted into the center of the wheel, on the hub side... it centers the wheel onto the hub by snugly fitting around the hub center and into the wheel.

i assume this wasnt a problem until you got the new tyres installed, so therefore it's not a car problem as much as it's probably a tyre problem. the only "car" problem i can assume from this may be a warped rotor due to improper torquing, but that wouldnt show up during acceleration unless the rotors a REALLY warped.