90+ shakes

I notice lately over the last few weeks that my 240 has developed some sort of vibration as the car approaches 90mph. Around 88 I can start to feel the wheel shaking a little bit, like driving over a bumpy road, then at about 90-92 the whole car has a moderate vibration.

If I maintain speed, the shake begins to oscillate, a moderate shake, that gets lighter and lighter until it disappears completely, then comes back and fades away again. If I coast at 90ish, the vibration is still there, which would support maybe the suspension or my tires not having primo balance any more (the tires are getting fairly old 30-40% life left on them, suspension is the original factory equipment.) I can't create the vibration at any RPM in a lower gear or anything..

Question: Do you think this is probably the tires and or worn out anything on the suspention, or could this be a more serious problem?

when you drive at 90 does it go away as you decrease in speed and/or does it go away if you exceed 90mph. If it does you probably just need your tires balanced.

However unlikely... Don't forget to check for slop in your wheel bearings. While wheel is off the ground, attempt to turn the wheel in and out as if you were trying to stear the wheel by hand. If there is ANY movement then the bearing has gone bad.