Tire warm-up wrap

A tire warm-up wrap, comprising a heat-generating narrow fabric woven from a warp having:

• (i) an electrically heat-generating flexible yarn which is made of a plurality of mixed yarn including between 20 and 60% by weight of discontinuous electrically conductive metal fibers and between 80 and 40% by weight of electrically non-conductive fibers;
• and
• (ii) a yarn composed of electrically non-conductive fibers, and (b) a weft composed of a yarn composed of electrically non-conductive fibers,
• wherein each of said mixed yarns includes at least 20 discontinuous electrically conductive metal fibers and is made by drafting a bundle of electrically conductive metal continuous filaments combined with a bundle of electrically non-conductive continuous filaments to stretch-cut at least the metal continuous filaments into a length of between 100 and 800 mm,
• wherein said electrically heat-generating flexible yarn has a line resistivity of between 0.05 and 10 ohm/cm and a resistivity coefficient of variation (CV) not larger than 10% and is made by subjecting the mixed yarn to a first twisting and then subjecting a plurality of the first-twisted mixed yarns to a second twisting under conditions such that the first-twisted mixed yarn has a first twist coefficient of between 6,500 and 13,500 and the ratio of the first twist coefficient to the second twist coefficient is between 0.5 and 1.50,
• wherein said heat-generating narrow fabric comprises in both of the lengthwise end portions thereof wefts which includes electrically conductive metal wires which are cut into a plurality of divided metal wire electrodes each having a short length, and
• wherein said electrically heat-generating flexible yarns of the warp and the respective divided metal wire electrodes form a series circuit extending forward and backward alternately along the length of the heat-generating narrow fabric between sets of the electrically heat-generating flexible yarns and between the divided metal wire electrodes in both of the lengthwise end portions thereof, wherein each of the set has a substantially equal number of the electrically heat-generating flexible yarns.