Well I guess I'll toss in my experience too. I have a stock 06' 1500 with 20"'s and the Hemi. At about 2500 miles I started feeling the vibration too. It has gotten worse. Mine is right at 35mph and 1100rpms. My Dodge dealer looked at it 4 times. The first three they couldn't figure anything out. So on the 4th, they replaced the driveshafts, balanced the tires, and added two pounds of weight to the exhaust. This still did not fix the problem. They had the district tech come in and look at it. The tech said "O, thats normal". Now Dodge refuses to look at it again. I took it to two local dealers, who both say there is a problem. BUT F*&# Dodge will not let them look at it further to fix the problem. Now I am suing Dodge under the New York State lemon law. I will never buy a Dodge again..........