vibration at 60mph or above on 2005 Cadillac DeVille DTS

vib. at 60mph+ .have tied new tires, new rims, balance, alignment. local cad. dealer no help.he can't find obvious reason, but question mechanics training and has 150,000 miles-has been maintained with care.

Find a Caddy or GM specialist. An alignment or tire shop may be able to help you.
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