Think in terms of anything that rotates could be cauing a problem and setting up a harmonic vibration. I bought new tires and had everything balanced and had a vibration still. Wheels were not properly aligned with just the lug nut holes and need hub centers to be "hub centric" or centered on the hub and vibration went away.
Do the shaking occur all the time or just at different speeds?
If you hit something hard enough to bend two wheels there could be collateral damage too, rotor, brake drum, hub assembly, axle or in short, anything that rotates in either front or back.
sorry