A bar code configuration which may be molded in the sidewall of a tire and has even surface portions and uneven surface portions for selectively reflecting light from a light source toward a receiving sensor to define bars of a bar code. The uneven surface portions may have grooves or ribs with a sawtooth cross section and sloped faces for reflecting light to a receiving sensor at an angle to the sidewall surface. The bar code configuration for tires molded in a particular mold may be provided by an insert fastened to the mold and having even surfaces and uneven surfaces at the inner mold face to mold the even surface portions and uneven surface portions of the bar code configuration in the tire sidewall as the tire is being vulcanized. By changing the insert the bar code configuration can be changed to provide different information about the tire.