My Aurora did it pretty bad with the Goodyear Eagle RSA'* it had on there stock. I swapped those out and put some Pirelli'* on it and the vibration is STILL there. It'* not as bad, but it'* still there. It'* annoying that such a nice car has that vibration problem on the highway, especially at most highway'* speed limit. Our 2000 SLE has it too, but the 2000 SSEi we own does not.. odd.. very odd!

(BTW, I have 16" rims, the SSEi and SLE both have 17" rims.)

Custom were they all low profile?

Nope, the SLE/SSEi have lower profile tires than my Aurora does. The overall height between the 17" rims + tires on the Bonneville, and my 16" rims + tire is the same height. My tires are basically an inch thicker than the Bonneville'*, and I still have the vibration problem..

Ya doent seem to matter what rim size is my 16s just as high as the 18'* with rubber
attached. Must be something to vibration other than the tires.

Just found this site and am happy to say this is my second Bonneville I have owned and strangely enough I am having the same problem with vibration as some of you have had. Dealer has informed me 3 of the tires are bad so they are going to replace them and the car only has 3000 miles on it. Why not all 4 I have no idea but GM does. I had a 2003 SSEI and now have a 2005 GXP, nice to see some people have nice things to say about a great car. I will let you know how the new tread works out and will be happy to post more as time goes by.