5/20    Recently a white line appeared on the treads of my car tire.  It goes
        around in a circle in the direction of the rotation.  Is it a sign
        that the tire should be replaced?  The treads are not bold yet.
        Thanks.
        \_ have it inspected?  Is it paint that you ran over?
        \_ Yes. The manufacturer of the tire intended it as an indicator
           that the tire needs to be replaced. --dim
           \_ Thanks.  I forgot to mention that the tire is Goodyear Wrangler.
        \_ Depends... the CA DMV says you can be down to something like 2mm
           or so and still be legal.  The test was the distance from the outer
           edge of a penny to the top of lincoln's head.  I personally think
           this is unsafe but the DMV says its ok.