I have a 2005 Colorado regular cab LS Z85 4X4 with I5 and 5-speed manual. The dealer has replaced 6 tires, including one of four Goodyear Wrangler RT/S (the replacement authorized by service bulletin PIT3107E dated 5/5/2005) and one General original equipment. They can't remedy the vibration at road speeds, and I have filed for arbitration with the State Board. I would apprciate any information from those having similar vibration problems, especially if anyone has had their vibration resolved.
The vibration, according to GM, is only with trucks manufactured before 8/2/04. Mine was manufactured in '04, but I don't know the date.
aforts@verizon.net