WIDE TIRE BEADS BLOW INNER TUBES

BLIN-01 Rev05

Problem: Coyote beadlock (BL) inner tube failures.

Overview: This BLIN is primarily intended to prepare the wide tire beads on large off-road tires to prevent inner tube failures in Coyote internal beadlock. It is recommended that the tire beads be ground as described below on all installations.

Background: The inside edge of all tire beads is very, very sharp. Further, large off-road tire beads are wider than normal tire beads. This varies by brand and is not exactly predictable by tire size. I’ve seen beads as wide as 1.25” (Fig. 1). The normal bead width specified by the Tire & Rim Association is ½ inch wide. This means that the sharp tire bead edge fits completely behind the bead bump.

Fig. 1

Here is a close-up of the sharp, saw-tooth bead edge (Fig. 2).

Fig. 2

Inner Tube Failures: Inner tubes fail in four ways:

1. Due to normal aging and use.

2. Due to being cut by the sharp, wide, inside edge of the tire bead. A slit tube (Fig. 3) is immediately obvious and unrepairable.

Fig. 3

3. Due to being punctured or pinched by the sawtooth edge of the wide tire bead. A puncture (red *) or pinches (right of red *) are shown in Fig. 4. Punctures or pinches that eventually fail may be repairable.

Fig. 4

4. Due to blowouts that are obvious. Blowouts may be due to either a failed tire bead sawtooth edge pinch (above and right of the red*) or a tire spoon pinch. Reparability varies.

Fig. 5

Solutions: There are several aspects to the solution, but all start with rounding, smoothing and eliminating the sharp, sawtooth, tire bead edge.

A) Using a small diameter (2”) drum sander (40 grit) or rough stone, as shown, round the sharp inside edge of all tire beads.

The hard-core rock crawlers have a special blade to remove this portion of the bead. They believe that a trimmed bead cures inside bead air leaks on conventional beadlock rims. Since Coyotes lock both beads, there is no problem for sure.

Left of the of the sanding drum is the sharp bead edge. To the right of the drum is the rounded tire bead. Your goal is to slightly round the sharp tire bead edge as shown in Fig. 7.

Does this make for leaky tires? I’ve never experienced or heard of rounding causing tire bead air leaks.

B) When mounting the final tire bead, pay particularly close attention to where the bead is placed in the rim. First, move the inner tube out of the way toward the inside of the drop center leaving space to put the outside tire bead directly on the metal and NOT the tube.

Fig. 6