I apologize for adding another damn vibration thread, but after 4 hours of searching, I just couldn't find anything that matched my situation.
I have a 2007 Access Cab 4x4 TRD Sport with 46k miles and all stock until I installed Bilstein 5100 adjustables up front set on 2.5" lift. I also installed Bilstein 5100's in the rear, but no additional lift. I have not had the rear spring TSB done. Now I have a vibration that starts at exactly 30 mph and increases in speed well above 80 mph. It does not change other than speed. I have not had it aligned yet and the tires are the OEM originals that are nearly shot. They get replaced next week with new rims.
The weird thing is, when I take it up above 30 mph so the vibration starts and then slow down to a stop, the vibration remains until I stop. When I take off again, it is gone until I hit 30 mph again. Also, putting the truck in 4WD eliminates the vibration.
Could this be the alignment, the tires, or the CV joints? I'm afraid to have it aligned if I find out that I just need to lower the shocks one level and get it realigned to fix it.