I purchased a used 2008 F150 with 62,000 miles. The truck is in excellent condition and is a crew cab with the short bed and the 4.6 v8 engine. I changed the 17 inch wheels to a set of Ford 18 inch wheels with Goodyear tires that came off another 2008 F150( XLT model). The tires had less than 15,000 miles on them. Since that time I have replaced 3 of the 4 tires because I could not get the tires to balance out properly. I have had all the tires and wheels balanced with the road pressure balance and the front and rear end have both been aligned. I CANNOT get the RIGHT REAR of the truck to keep from bouncing and hopping at almost any speed. It changes from day to day a little bit but while slowing down I get the hop vibration( when I apply my brakes) and while at speed ( mostly 45-55) and above 65 I can constantly feel the truck vibrating. It is apparent it is the right rear. I took it back to the dealership where I bought it used , they could not find any issue. At some time, the rear cover to the rear end has been taken off but I cannot find any information through normal channels as to why. I was told by a Goodyear dealer it is a KNOWN problem with this truck but no one else advises that. I was by the shop that balanced the tires it is a Goodyear problem. All I know is that I cannot enjoy my ride due to this very apparent hop/bounce from the rear end. The alignment shop said they could not do anything more to make it better. Is there a FIX to this? Is it a problem with this model truck? Any suggestions greatly appreciated. The truck has 69,000 miles on it now.