In the tire rebuilding process, additional markings are engraved or embossed on the sidewall. See figure 11-14. First, R or TR followed by a number identifies the number of times the tire has been rebuilt. Next, the Julian date of the tires rebuilding is added. Finally, the name of the rebuilder and plant location is added.

Tube tires with inflation pressures greater than 100 psi and all tubeless tires must be suitably vented to relieve trapped air. Tube tires are vented in one of two ways. The first method uses air bleed ridges on the inside tire surface and grooves on the bead faces. The ridges and grooves channel the air trapped between the inner tube and the tire to the outside. The

Figure 11-14.Rebuilt tire identification markings.

Figure 11-15.Tire storage rack (varied size tires).

second method uses four or more vent holes that extend completely through each tire sidewall. They relieve both pocketed air and air that accumulates in the cord body by normal diffusion through the inner tube and tire. Tube tire vent holes are marked with an aluminum- or white-colored dot.

Tubeless tires have vent holes that penetrate from the outside of the tire sidewall to the outer plies of the cord body. They relieve air that accumulates in the cord body by normal diffusion through the tubeless tire liner and the tire carcass. Vent holes in tubeless tires are marked with a bright green dot.

NOTE: Rebuilt tires may not have the vent holes clearly marked.