ive had my 15 sierra for 2 weeks now, it did have a tire shake at 73mph. it did sit on the lot for 2 days short of a year so i kinda expected it. replaced all the tires under warranty. super smooth now.
now the the pico scope has been in all dealers for a few months now its become much easier and faster for us to track down the vibrations going on in these trucks. vibration problems are becoming few and far between these days.