I've had my green Prius since Aug 2000. Some 22,000 miles later I've noticed some wear on the tires. I went shopping for tires and was told (by a sears mechanic) not to install "on the shelf" replacement tires. I was told that because of the vehicle load that I needed to use the Bridgestone "Extra Load" tires. Has anyone heard this? Is anyone using other than the issued extra load tires that came with the car?