Pulsing Vibration - 2004 Corvette (Hatchback)

I'm posting this for a friend. He has a 2004 Vette. New Kuhmo tires. Hatchback (if relevant). Rims balanced. When he gets to 75-80 mph, he gets a pulsing vibration in the rear section of the
car. Dealer could not find the problem. When he's doing 80, he puts the car in neutral and the vibration is still evident, so this may mean that it is not transmission related.
Has anyone any experience with this symptom? Any inputs that help us to get to the bottom of this mystery will be appreciated.
You'll probably ask whether he had this symptom prior to putting the new tires on and balancing the rims. Can't say. Vehicle was recently purchased. New tires were put on immediately. Pulsing symptom wasn't noticed until afterwards.
Phoenix, Arizona
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

i've had a warped disk rotor cause this. it only occurred when getting over 60; up to that it was ok (or at least not noticeable).
regards, charlie cave creek, az
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
danhilde wrote:

different Kuhmos for that car. Another choice might be better. -- PJ
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Until after the tires? Boy, that sure seems to tell, doesn't it?
I've had some issues on my C5, twice, related to a shudder but just while breaking, once was a rotor, once was a loose control arm.
But if it started after the tires... are they unidirectional, and if so, are they on the right side?
Have someone else balance the tires - it might have thrown a balance weight of the rim.
Venger
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.