Various different types of tire tread wear indicators are known in the prior art to indicate when a tread has worn to a level where the tire is no longer safe for use. On such tread wear indicator is shown in U.S. Pat. No. 5,303,756 issued to J L Hill which shows the use of wear indicating members in the shape of pins or pegs molded in the tread material adjacent the inner surface of the tread. These members are made in a color contrasting to the color of the tread so that as the tread wears to a certain level the wear indicators become visible. U.S. Pat. No. 4,226,274 issued to H Y Awaya, et al. shows another example of the use of contrasting colored indicia embedded in the tread to indicate the amount of tread remaining and when the tread has worn to an unsafe level. Likewise U.S. Pat. No. 3,516,467 issued to C D Simms shows a tire tread having annular ribs of a contrasting colored material embedded at the radially inner portion of the tread in such a position that when the tread wears to a certain depth, the ribs become visible. A similar concept is shown in U.S. Pat. No. 3,833,040 issued to C G Bins. U.S. Statutory Invention Registration No. H1283 shows a tire having plies of contrasting colors to each other and with a bottom ply having a contrasting pattern so that various levels of wear are indicated by the different colored plies and the bottom ply serves as a warning of an unsafe condition. U.S. Pat. No. 2,706,509 issued to E J White indicates various levels of tire wear by means of stepped surfaces located in the voids or grooves between adjacent ribs of a tire. This indicator will show for example of whether the tread is worn one-forth, one-half or to some other level for the purpose of providing a price adjustment on a tire which may fail before the tread is fully worn.
While the above described tread wear indicators may function as various levels of effectiveness for the purposes for which they were designed, none of the above wear indicators was designed for the purpose of indicating when a tire should be rotated from one wheel location to another on a vehicle to compensate for any uneven tread wear and extend the life of the tire.