1. Adjust shape of apex core.
2. Enlarge, thicken apex core, strengthen bead area and reduce the stress at bead area. The height of vulcanized apex core was increased from the original 80mm to 95mm, and thickness of bead area was strengthened from the original 27mm to 33mm.
After adjustment, we made endurance test on relevant tires, the result was obviously improved than before. take 295/75R22.5 TX35 as example, before adjustment, when the test reached to 135.28 hours, abnormal smell happened from the endurance machine and alarm sounded. after adjustment, there was nothing abnormal detected after 200 hours of the test.