2004 Chevy Silverado Shaking

My truck has started shaking when driving. Usually at higher speeds. Today while traveling home on the freeway when I hit some bumps it started shaking violently and I had to slow down considerably for them to stop. I continued home with the lesser shaking going on. My tires are at a low tread but now I'm thinking maybe its not the tires that are causing this. Can anybody help me please!