bouncing/vibration in drivers side front

I have a 2002 gmc 2500hd that feels like it is bouncing or shaking back and forth in the drivers side front.I thought it was maybe the tires so i put new tires on it.still does it.so i took it back to have them check the balance of the tire,still does it.It does'nt start doing it until i reach about 45mph then kind of plains out at about 60mph.A friend of mine has an 03 2500hd duramax diesel and it does the same thing.Any help!!!!!!!!!

Seat vibration and bouncing is usually a problem in the rear.Since its a 2500 It's probably equiped with 10 ply rated tires. I would lower the air pressure when empty to about 45PSI or the minimum amout on the sidewall of the tire. This will give you a softer ride. Check for an out of round tire, and you can also put a jack under the differential and spin the rear tires checking for the vibrations. At about 90K miles you might consider shocks too if you've logged any heavy towing miles.

Actually u can feel it in the steering wheel and on your feet.It actually feels like the wheel might fall off.It`s like the wheel is wobbling back and forth.any more info would be great.Thanks ahead of time.

Actually u can feel it in the steering wheel and on your feet.It actually feels like the wheel might fall off.It`s like the wheel is wobbling back and forth.any more info would be great.Thanks ahead of time.
Looks like it might be a bent wheel to me. If its that bad,the tire shop should be able to find the problem.