Well, depends on how you are determining the wobble...visually, it can look like a wobble if the wheel is bent, the sidewalls are uneven, visual distortion caused by discoloration (dirt, wet, etc) and so on.
If it's not visual, and just something you are feeling, could be sidewalls flexing (no personal experience with the tires you are running), vibration caused by wheel, tire, driveline imbalance (one, some, or all of these) or loose/broken components like the leaf spring pins.
Just some ideas, when did you start noticing it?