97 Tahoe, vibration at 65 mph

We have a 97 Tahoe that has quite a bad vibration at 65 mph. We had a front end alignment about two months ago. We got new tires about a month ago. This vibration started as a once in a while type thing. Now it is regular. It also does the vibration thing when decelerating - generally from about 45 or 50mph.

if there is no new noises with it my guess would be tire balance (they tend to slip on the rim at first with the bead lube) but what shape are the u-joints in?

check ujoints, I just did em same thing happening to me

I have a similar problem w/ my 1997 tahoe has a shimmy in steering at low speed. I had it checked and they (Garrage) had to replace the Pit arm and Idler arm but the problem has not completely fixed but with the new parts itsn't as bad as it was. I know the vehicle requires new set of tires and i hope this will solve this problem.

I work at a tire shop and we get this sort of thing alllll the time. The U-Joints are a good starting point because I replaced mine when getting an odd vibration at speed and one of the clips were gone and a cap was coming off. Another suggestion is that you take a feel of your tires. A 97 with old shocks could cause chopping out on your tires. If you notice a rough texture to the overall tread of your tires than that can easily be the source of the vibration.

I had the same problem with my 99, turned out the shocks were shot at 65,000 miles.