Originally Posted by
dski
screw a hand brush to the bottom of a rubbermaid container, fill with water and simple green, then scrub.
Just make sure the water level is a little below the tops of the bristles so you're not submerging the tire too much. This works great. Any type of dirt/clay will come off easily, even when dried on. Blow the excess water off the tires with a compressor and dry with a towel. They come out so clean they will actually stick together when you stack them.