I went from 17" wheels to 19" wheels and now my car vibrates above 70 mph. Its kind of random and doesn't increase/decrease in any repeatable fashion. It vibrates less as I slow down, and once I speed up the vibration kind of catches up and then goes away, comes back...etc

I've searched, but all the info was about front suspension parts. I've rode in a friends 88 7-series with bad thrust bushings, etc and know what that feels like. This doesn't seem to be coming from the front as my wheel doesn't vibrate, not a brake issue, its only a under the car / in the seat thing. I don't think its the driveshaft either b/c I replaced the clutch and drove home on the 17's smooth as glass. Basically it went from a 7-series ride to vibrations only when the wheels were changed. I'm sure the bigger sidewalls on the 17"s absorbed whatever vibration is present now.

What suspension components in the rear can cause this? I've looked at the bushings and they seem ok. I haven't gotten an alignment yet, but the overall tire size is pretty close. Has anyone had an experience where an alignment problem caused a vibration? I know it affects tire wear, etc.

Thanks in advance.

Make sure the wheels are balanced properly. What makes you think that it is suspension specifically?

I balanced the wheels at work with our Hunter Roadforce Balancer. They 0.00'ed out perfect and didn't take much weight. The vibration started with my last set of 19's but I had spacers in the rear. I thought that was the cause, but the vibration still occurs with this set of wheels. It did vibrate worse with the old set though. Its not terrible, just annoying. I'll check the alignment this week and see what I come up with so I can narrow down a possible cause. The car does sit up a little higher with the 19's, and from what I've read the suspension of BMW's changes a lot with ride height.

Have you checked the hub fit of the rims? AFAIK, these are hubcentric fits.

Regards

Yes 74.1mm center bore.

Take em off, clean the hubs up to remove any scale (and don't forget to rub em w/ a very wee bit of wheel bearing grease on the hubcentric mating surface so they don't stick), put the wheels back on, make sure they are flush on the hub and torque em in the air by hand to 65, then 85.

Sometimes they are just a hair off...Especially if you torqued em sitting on the ground.

Ok, I'll try that. I love the wagon btw!:buttrock

Misalignment causing vibration seems quite reasonable, especially with such huge wheels.

Yes 74.1mm center bore.

Wait.. 74.1? E34 hub bore is 72.5... You'll need hub centric rings..

I totally missed that!!!