I wanted to share my experience aligning the rear of my 2004 Prius with 104,000 miles. Just bought the car and it needed tires. I decided on the Ecopia EP100's and I also paid for a lifetime alignment at the local tire store. These were the before and after of the initial alignment. Before After As you can see the left rear alignment was just out of spec. The car would wander at freeway speeds, it just didn't feel right. It seemed as if the car required continuous steering inputs to stay in the lane. I was suspicious of the rear alignment causing the problem and it was suggested to me by other forum members to correct it. The following are the steps I took to correct the camber and the toe of the left rear of my car with an adjustable shim. I bought the shim at the local NAPA auto for $13.99. It came with instructions but not for the Prius. I hunted the net for the correct Prius instructions and found this handy calculator. You enter the adjustment amounts for toe and camber and it calculates the settings for the adjustable shim. In my case -0.20deg toe and -0.20deg camber were just what I needed to match the right side and bring the left side into spec. 25 was the outer ring number and 8 the inner ring number. After cutting out the template for the Prius hub bolts. Rear hub after removal from axle. Mating surfaces cleaned for proper seating of shim. Shim installed on hub. Hub reinstalled into axle with shim. Bolts torqued to Toyota spec plus 15% or 52ft-lbs per instructions. Put the drum back on and the wheel and off to the tire shop for alignment check.