TSB : Tires, Damage Due To Mounting Error, Damage From Fitting The Tire

Details

Bead Bundle Broken During Tire Inflation Modern radial car tires are mounted only on safety rims. These have a hump -1- running along the shoulders. Fig 1: Identifying Wheel Components (Cross-Sectional View) Courtesy of VOLKSWAGEN UNITED STATES, INC. Hump (double hump H 2, extended double hump EH2) Rim flange Inner bead seat (e.g. oblique seat) Rim Wheel disc Bed Outer bead seat (e.g. oblique seat) The hump prevents the tire from being pressed out of the bead seat during travel with insufficient tire pressure. When the tire is inflated, the tire bead may not slip completely over the outer rim hump. In this case, there is the danger that the bead bundle will be overstretched if the tire pressure is too high and the steel wires rupture partially or completely. Torn bead bundles are often not detectable from outside. Special Information for Run-Flat Tires Rims with an extended double hump (extended hump EH2) are required for run-flat tires. Refer to DISC WHEEL STRUCTURE . The extended double hump prevents the low tires from slipping from the rim when flat. NOTE: To prevent damage when assembling, follow the instructions for mounting run-flat tires. Refer to Removal and Installation . WARNING: Tires with damaged bead bundles are not seated safely and securely on the rim. Such tires are a safety risk! In addition, there is the danger that a partially broken bead bundle tears during continued operation and the tire suddenly tears open. If the bead bundle breaks during inflation, the carcass will also be destroyed. Tires with Broken Bead Bundle and Destroyed Carcass Fig 2: Tire With Broken Bead Bundle & Destroyed Carcass Courtesy of VOLKSWAGEN UNITED STATES, INC. Illustration shows a tire with broken bead bundle and destroyed carcass caused by an excessive pulling force during fitting. Bead Damage by Faulty or Incorrect Wheel Mounting Using Tire Changers The following mistakes when fitting tires can lead to severe tire damage. When rolling in the upper bead on the tire changer, the opposing tire bead does not lie completely in its bed. Refer to TIRES, DAMAGE DUE TO MOUNTING ERROR, DAMAGE FROM FITTING THE TIRE Bed . When the fitting head was incorrectly adjusted When the edge of the fitting roller rolls onto the bead When the guide rollers are worn or have sharp edges Tire with Bead Split Open Fig 3: Tire With Bead Split Open Courtesy of VOLKSWAGEN UNITED STATES, INC. In these cases, the bead, which is under great tension, can be cut into in the direction of rotation, split open and/or be crushed down to the bead bundle. Frequently, mounting and run out marks from the guide rollers are identified in the damaged area. NOTE: Both tire beads as well as the bead seats must always be coated with fitting paste. If mounting damage is undetected, there is the danger that the tire will fail later when driving. THEREFORE! Never fit a tire without fitting paste. Do not inflate the bead seating pressure above 3 bar (44 PSI). Do not inflate the tire filling pressure above 4 bar (58 PSI). After the tire has been fitted, reduce the air pressure to the specified value.