Unless you specifically need the driver for the relative offset, turn off relative offset and remove the driver.
The Object Offset doesn't work the way you're expecting it to. The second item in the array will be moved the same distance from the first item, as the first item is from the empty. The second item will be rotated as many degrees from the first, as the first is from the empty.
So, to get the effect you want follow these steps:
NOTE: Even if the origin of your rim "piece" is already supposed to be at the center of the rim, these instructions will be the same. You'll just have a few things on top of each other.
- Set the array "Count" to 1 (just for now)
- Place the first element on the rim exactly where it should be
- Place the empty in the exact same location as that element, with the exact same rotation as the element
- Place the 3D cursor at the EXACT CENTER of your existing rim
- Change your pivot center to "3D Cursor"
- Select the element (without selecting the empty)
- Set your array count to the number of elements you want to end up with (5, I think?)
- Then rotate just that first element and the rest will project ahead of it
- Adjust until the desired effect is achieved
Hope that helps!