The last few times I've had something like this happen it ended up simply being tires were out of balance. It happens from time to time and depending on where you got the tires from, it should be a simple fix. Although I will admit it was on a 2wd S-10, a couple times on my 85 c10, and my old Malibu. I haven't felt it from the tires on my 4wd yet.
One question though, the vibrations, do you feel it in the steering wheel, or on your feet like it's coming from the floor boards?
One question though, the vibrations, do you feel it in the steering wheel, or on your feet like it's coming from the floor boards?