Abstract: At 8:00 p.m. on December 18, 2021, Employee #1 and Employee #2 were changing the right rear trailer tires on a Dragon Water tanker trailer (VIN #: 1URST422382068551) attached to Peterbilt truck (VIN#: 1XP-5D68X-X-TD373380). Employee #1, a water haul driver, and Employee #2, the shop supervisor, utilized flammable liquids, which were sprayed into the tire and ignited to seat the bead of the tire onto the single piece rim wheel. Vapors from the tanker, which had hauled approximately 40% methanol/60% water, were ignited by the flames and flashed back to the tanker, causing a pressure explosion. The ignition of vapors, which flashed back into a tanker trailer caused the tanker rear most top hatch and rear facing hatch to explode off with an ensuing fireball. Employee #1 was killed and Employee #2 sustained severe burns to the face and hands and was hospitalized for treatment.