Well, it depends on how much lift you got. I just installed a 3 inch suspension lift a couple of weeks ago. I run 31 inch All Terrains and mine rides smooth as silk. It may be the tires (I've never ran mud terrains so I'm not sure), but if your lift is 4 inches or over then it's possible you will need some more equipment to eliminate the vibration.
2000 Ford Explorer
Looking for a YJ!