Vibration in front end of car that increase's with speed of car

check for warped disc rotors, loose wheel bearings or failing cv joints

Sounds like a wheel out of balance,tire low on air, tire belt shifted (starting to go), loose wheel, bad wheel bearing. press the helpful button and check links below
Diagnosing And Repairing Wheel Vibration

Shakes and Wobbles

I would say you have a problem with the steering part of car, have a mechanic look at it

could be tires need balancing or front end alinement

wheels could be out of balance

I'd have to check your suspension. You think the tires are ok? Did you try rotating the tires to see if it made any difference?

First check the easy things, tie rod ends, ball joints, etc.I did all of this on my 2001 Aurora with 150K miles on it and still had vibration. The fix was to replace the half-axles. The old ones were worn and had a lot of play in them. I would get vibration as the speed increased.The parts cost me about $60.00/ea. I installed them by removing the bolts on the front struts, the axle nut, tie rod end, and brake caliper. You need to get enough room to remove and install the axle without putting too much bend in it. Over flexing the shaft can damage it.

vibration that slows or stops when turning is an indication of a bad hub bearing

IF IT ONLY THUMPS WHEN YOUR CAR IS MOVING YOU COULD BE WRITE. PAY ATTENTION TO THE THUMPING CLOSLEY, DO YOU FEEL A VIBRATION IN THE STEERING WHEEL, IF SO THE PROBLEM IS IN THE FRONT END. IF YOU FEEL A VIBRATION IN THE DRIVERS SEAT THE PROBLEM IS IH THE REAR END. YES THE VIBRATION FROM THE FRONT STEERING AND THE DRIVERS SEAT IS A WAY TO TELL WHERE THE PROBLEM IS

I had similar problem with my 03 trailblazer. It had a low dull hum in the front end with a little vibration being felt in gas pedal. Noise increased over a couple weeks and was louder turning to the left and quiter turning to right. A GM mechanic friend of mine replaced the front right hub and took care of the problem. Hub was about $160 at Autozone.