ON 8/3/2009 AT 1730 AND 2045 HOURS I WAS DRIVING MY 2006 F250 SUPERDUTY 4X4 ON I-10 EASTBOUND AND DROVE OVER A BRIDGE/CULVERT SEAM IN THE ROADWAY. THE LEFT FRONT WHEEL AND STEERING WHEEL SHOOK VIOLENTLY AND WOULD NOT STOP SHAKING UNTIL MY SPEED SLOWED FROM 70 TO 25 MPH. IT WAS NEARLY IMPOSSIBLE TO BRAKE WITH CONSTANT PRESSURE. I HAD TO FEATHER THE BRAKE TO SLOW THE VEHICLE. I INSPECTED THE VEHICLE TO THE BEST OF MY ABILITY AND SAW NOTHING OBVIOUSLY WRONG. THE SECOND INCIDENT OCCURRED IN THE RAIN IN THE DARK AT 70 MPH. MY WIFE WAS DRIVING AND WAS SCARED TO DEATH. BOTH INCIDENTS NEARLY CAUSED ACCIDENTS WITH VEHICLES BEHIND US. I INJURED MY LEFT SHOULDER ON THE FIRST ONE THAT'S WHY MY WIFE DROVE BACK. I RETURNED HOME AT 65-70 MPH AND HAD NO FURTHER INCIDENTS. I CHECKED THE TIRE PRESSURE ON THE 31 INCH BFG'S AND IT WAS ACCURATE AND WITHIN THEIR SPECS. *TR