I have a new 08 F150 that shakes pretty bad at 55-58 mph. Rather smooth up to that speed and then after 60 mph. The dealership has road force balanced the tires and states that they all pass. When driving the left rear corner of the bed is shaking pretty bad, but the rest of the truck seems smooth so I'm thinking it's the left rear tire, but they tell me it is balanced. Any ideas?

Thanks!

 

There have been lots of posts regarding this 50 mph vibe. Mine did it after I put my 33" Toyos on, but RF balance indicated that the left rear was 67 lbs....too high. They replaced the tire and it's very, very smooth now at all speeds.

Check your tire pressure...s/b around 35 psi front and rear with stock tires. I'm running 42 front and 40 rear. Also, if you have the tools, jack the rear up and place on jack stands. Start the truck and put in gear. Watch the rear tires as they rotate and see if there is a highspot. That is how I determined my left rear was out of whack. New tire, all good.

 

Do you have Pirelli Scorpions on the truck?

 

I've got BFG P275/65RX18 OWL All Terrain.

 

Then you either have a bad tire or a balancing problem. Take them to Discount tire and have them rotate and balance all 4 tires.

 

i hate BFG's lol i had the same tires with the same problem for 2 years started rightaway i got them balanced about 50 times in the 2 years i had them and just this week i got a new set of tires.... wobble gone i think those BFG'a are just crap and the tire dealer said my problem with the bfG's is actually a pretty common problem, just a poor design.

 

Dealer wants to install a damper or dampner to eliminate the vibration... anyone have this installed on their truck? Did it work??

 

More than likely a balancing issue, does it vibrate through the steering wheel or seat? Seat equals rear, st wheel front. Switch tires front to back to see if it changes.

 

I feel the vibration in the steering wheel and seat, plus you can actually see the left rear corner of the bed bouncing. The right side of the bed seems to be smooth. They have already road force balanced the tires... no difference.

 

Third trip back to the dealer and they road force balanced the tires for the second time. Two of the tires were out of balance. They installed the damper and the vibration/shaking still exists! Dealer does not know what to do next... they mentioned putting a set of Michilen tires on. They are supposed to be a softer, better riding tire. Wondering if it is a drive shaft issue now...

 

Does it shake first thing in the morning? After several miles? My Pirellis flatspotted terribly overnight. Once they warmed up, the shake was gone. The steering shimmy was still there on the interstate regardless of time. With my Toyo's, everything is fine, no steering shimmy or shaking.

 

If when the truck is parked and you stand on the left side of the bed and jump up and down and do the same on the right does the left bounce more or less then the right?

 

The truck as vibration all the time... no matter how long or what time I drive it.

 

Dealership normally isnt the best place to work out a tire issue. They normally dont have good tire techs.
Something you can do on our own, there should be a dot either red or white on the widewall of the tire, normally closer to the bead. Once you find that, see if it is mounted close to the valve hole in the rim. Thats called match mounting. The dot is the highside of the tire where its put together. If they are not close that could be causeing your problem. Have them spin the tire 180deg on the rim. Also, have them spin the rim by itself, problem might be on the rim.
I have the same problem with a set of pirellis atr's and have had them balanced on 3 different sets of 20' rims and cant get the shake out of them at 55. So i put them on the rear and just dont ride at 55. Ill either replace them with a set of Falken STz01 or Kumho STX's.

 

Ford told the Dealer to replace two of the tires which had slightly higher Road force balancing ratings. This seems to have done the trick. Vibration seems to be gone. Guess it was the BFG bad tire issue that I've read so much about. Thanks to everyone for all the help and advise.