Just purchased this car for my son. The rear end vibrates at speeds over 65 MPH but runs fine at lower speeds. Had tires rotated but they are more than 50% worn.

Hi Walter

Was the vibration apparent before the tires were rotated?
If not, I'd suspect a broken belt or bent rim.

Hope this is helpful.
-Steve

I'd start by having the tires balanced and remounted. Rotating them wouldn't hurt either. Start there.

check your wheels balance,If the problem still check your rims whether you have any slight bend,

I'd have to check your suspension. You think the tires are ok? Did you try rotating the tires to see if it made any difference?

have the tires themselves checked, it sounds like you have a tread coming lose , also, have you had the front end aligned

tires are the number one problem for highway speed vibration (assuming your engine is running ok).

Have them balanced and rotated and have them check the roundness (or lack thereof) while the tire and wheel are on the computerized wheel balancer.

i would suspect somewhere in your front end you have a compliance bushing with excessive movement. these cars front ends depend heavily on these style bushings, and as they wear you can start to see tire wear patterns, looseness in steering, and high speed vibration. make sure you have the front end inspected by a shop that is familier with these types of cars. good luck!

Get your tires balanced. Most likely you have had a hole patched in the tire at some point and they did not balance the tire. (Left rear)

do you feel any vibration when braking at lower speeds like 30? if any vibrations happen only when braking, fix those first. I suspect there is a rear brake problem. also verify that the driveshaft and universal joints are good.

Most computer controlled tire balancing machines which are in use today only balance tires to between 65/70 miles an hour. To get them balanced to a higher speed you might want to call a few auto performance shops and see if they balance tires to a higher speed. At higher speeds it takes very little in the way of an off balanced tire to really set up a vibration so shake.

bigc