Dodge Ram Man
So I drive a lot of highway miles where the speed limit is 75mph - 80mph and when I'm doing more than 80mph I get a bad vibration through the entire truck. It's weird, I don't really know how to describe it because it is an off an on vibration. So I'll be going 85mph and it will vibrate like I'm on the shoulder hitting the little bumps, not quite as bad as if you actually do that, but it does that for a while then goes away for about 3 seconds then does it again for about 4 seconds then repeats. My tires are Nitto Terra All-Terrain and they are low on tread. I thought they may be the cause but if it is the tires then why is it off and on? Also it doesn't get worse as I go faster it just stays the same. I took it up to 105mph and it still did it the same as 80mph. It just starts at 80mph and stays there until I go back below that. Is it my driveshaft, transmission, axle? I had Motive 4.56s installed but it was doing this same thing way before I had them installed. The only thing I've done that may do something towards that is my Flashpaw 3840 with the Performance 91 tune...may affect it or may not I don't know. Anyone know anything about this?