Besides bent rims and or bad tires what else can cause serious car shaking at high speeds?

Answer 1

A bent hub flange or axle flange can cause this. This can also happen if a wheel rim fits poorly to the brake rotor/drum due to being an incorrect rim for the vehicle or buildup of rust on hub/axle/brake rotor/ brake drum/ wheel rim. Missing centering adapters or incorrect lug nut seating can also cause an off center or out-of plane wheel rim mounting on the vehicle.

Damaged or unbalanced drive axles, driveshafts, and related bearings can cause such vibrations.

Loose wheel bearings can cause these vibrations also.

NEVER let anyone tell you that your shocks can do this. You can take your shocks off and it will NOT cause a shake. It sounds like you might have a bad tie rod end. , Ray

For a possible simpler fix, try having your tires balanced, rotated, and aligned. This can work wonders. Even a simple balancing may do the trick.

could be a bad u joint

If there is a build up of mud or ice frozen on the rim. Steering dampner or u-joint IF you have either, something embedded into the tire such as tar, loose chassis parts such as tie rod ends as mentioned, play in a rack, loose rack mounts, out of balance wheel. NOT alignment.

I had the same problem a few months ago. It turned out to be a split in one of my rear tyres; quite a large split in fact, the tread had badly come away from the main tyre. It was (apparently) most likely caused by salt/grit on the roads building up in my tread then swelling in wet weather. My mechanic automatically went to rebalance my wheels when I reported it but then found the tear, he was surprised that it was causing such a violent shudder and even more surprised that it hadn't burst!