Ok.. just bought myself a new 08 fx4 supercrew and I have a little bit of vibration going around 70mph in the steering wheel and truck itself. It's not too bad, but it kinda feels like the truck rumbles a little more than it should. lol..

Well, anywho I just had a 6" procomp lift thrown on and the rumbling feels about the same, so I'm assuming it has something to do with my tires instead? I figured being stock 20" wheels and Pirelli tires and all, they should be balanced or what not, but there is definately some minor rumbling in the steering wheel going 70mph.

I'm fixing to go have my new 35/12.5 r20 Toyo MTs thrown on tomorrow morning, and have an alingment for the lift, hopefully this will remedy the situation.

My question is, all things considered, what is most likely the cause of the vibrations in my truck? It's practically brand new, and was rumbling just the same before I put on the lift, so I kinda wanna rule out that possibility, but if for some reason the suspension is causing this, please let me know, I drive in 2wd.

 

Probably a tire out of balance.

 

I have the same issue on my '05 FX4. Been that way for awhile, no clue what it is. Only at 70mph+ like you said. It's a small but noticable vibration in the steering wheel and depending on the highway it could be more or less noticable.

I've always figured it was something with the tires but rotation didnt really affect anything last time.

 

I'll second that. Also possible mild flat spotting from sitting on the lot.

 

I would also go with a wheel being out of balance.

 

i have major rumbling on my 04 screw never bothered to fix it or find out what it is

 

I had this same problem and found out that one of the weights used to balance the wheel had come off. Some newer weights instead of crimping onto the rim have double sided sticky tape and after a good power wash i had inadvertently washed one off. This caused my rumbling at high speeds because of how fast i was going and with it only being one weight it wasn't noticeable at slower speeds.