Bead core ruptured while inflating tire
Pic. 4.26. The scheme of mounting the tire on the disk: 1 - hump (double hump H 2); 2 – side edge of the rim; 3 - inner shoulder of the rim (e.g. conical shelf); 4 - rim; 5 - disk; 6 - cavity; 7 - outer shoulder of the rim (e.g. conical shelf)
Modern radial tires for passenger cars are mounted exclusively on safe rims. Their rims have elevation 1 on the shoulders around the entire circumference (pic. 4.26).
The hump protects the tire when driving with low air pressure in it from slipping off the shoulder of the rim.
When inflating a tire, it may happen that the tire bead does not move completely through the outer hump of the rim.
In this case, there is a danger of overstretching the bead core at too high a pressure, as a result of which its steel strands will break partially or completely. The rupture of the bead core is invisible from the outside.
Attention: Tires with a damaged bead core do not fit snugly on the rim. These tires are extremely dangerous to use.
Attention: In addition, there is a risk that a torn bead core will rupture completely in motion, and the tire will suddenly explode. If the bead core breaks when the tire is inflated, the carcass is also destroyed.
Tire with broken bead core and broken carcass
Pic. 4.27. Tire with broken core
Figure 4.27 shows a tire with a broken core and broken carcass as a result of overstretching during mounting.
Bead damage due to erroneous or incorrect tire fitting on a tire changer
The following tire fitting errors can cause serious tire damage:
- if, when rolling the upper bead on the tire changer, the opposite bead of the tire does not lie completely in the cavity;
- if the mounting head has been adjusted incorrectly;
- if the edge of the mounting roller rolls along the side roller;
- worn or sharp guide rollers.
Tires with bead cut
Pic. 4.28. Tires with bead cut
In such cases, the high voltage bead may be notched, cut and/or pinched down to the core wire (pic. 4.28).
Often, traces of the beginning and end of contact with the guide roller are visible in the damage zone.
Note: In principle, both tire beads and rim shoulders must be lubricated with tire fitting paste.
Note: If mounting damage is left unnoticed, there is a risk of the tire breaking during further use.
Note: Never mount tires without mounting paste.
Note: Do not pump explosively above 3 bar.
Note: Do not inflate tires above 4 bar.
Note: At the end of tire fitting, deflate the tire to the prescribed pressure.
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