My van vibrates only at 55mph. I’ve rotated an balanced the tires. The guy that did this said that one wheel seemed to be bulging a little. We put it in the back and the vibrations didn’t change. Do I buy 4 new tires, put new bearings inn, or are my U joints bad?
You should be able to wiggle the drive shaft to see if your U-joints have any play in them. You could even put the back of the van up on secure blocks and spin the wheels to 55 mph. See if the vibration exists. If it does, remove both tires and try it again (which could help you determine if your drive shaft/u-joints are bad).
Make sure you don’t use concrete blocks to support your van - very unsafe.
You can grab driveshaft and turn back and forth to see if there is any play in u joints
A wheel is “bulging a little”? I’m not sure how a steel or alloy wheel could “bulge”.
Is it possible that you are trying to tell us that one of the tires has a bulge in it? If that is the case, then that tire is a time bomb waiting to detonate, so to speak.
Tires with a bulge are no longer safe to use, and this tire should be replaced right away. Once that tire is replaced, there is a very strong probability that your vibration problem will go away.