Tread Separation Damage

This is not fun, especially if it happens when you’re far from home. I should have replaced the tires on the Overlander, since it had been in “dry dock” for about 4 years, but they looked so good…

The tire tread failed just outside Idaho Falls. The core still held pressure, so getting to town at low
speed didn’t require putting on the spare. Commercial Tires didn’t have any bias ply 7.00/15s in stock, so they suggested radial 225/75R15 as a close replacement. They even mounted one and did a trial fit, just to make sure. I couldn’t tell the difference, so I replaced all 4.

When the tread comes off, you get two kinds of damage. First, the skin is not closely trimmed to the
front outrigger, so the tread beats it down and generally cracks the skin for several inches. This is cosmetic damage. The other damage is the inner plastic whell well liner get cracked and usually gets torn away from the shell, allowing pink fiberglass to hang down and allowing the liner to rub on the
tire(s).

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After getting new tires, the first order of busines was to stop the loss of insulation and get the liner off the tires. The spring clamps in the above photo worked fine–even drove about 40 miles using only the clamps (4 of them) to hold the plaster liner to the shell.

To fix the skin I cut away most of the bent aluminum and drilled a few stress relief holes where the cracks seemed to be headed. The next step was cutting a patch and a length of 3/4″ L-extrusion to
hold the edge of the patch firmly against the outrigger. The vertical web of the extrusion was placed between the existing rub panel and the outrigger, so that there is no edge for any future separated tread to hit/grab.

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Trimming the banana skin back to the edge of the outrigger required the skin at the front of the wheel well to be trimmed and re-faired. Make sure you get the trim back on. Otherwise, you have a sharp edge that will be a hazard the next time the wheels are removed.

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The outer end of the L-extrusion needed a small amount of curve to fit the outrigger (thanks, shrinker tool). A little additional persusion from a plastic mallet got it fitting tight. You can’t see the repair unless you get your eye level down below the axle mounting plate.

Reattaching the liner to the skin is a big problem. The liner doesn’t have a lot of extra margin along the edge to allow easily riveting it back in place. In addition, if you don’t have rivet washers or some long piece of thin aluminum to act as backing, the rivets probably won’t hold. Fortunately there was a metal dealer near the tire shop who had 12′ x 1-1/2″ x 1/8 pieces of aluminum in stock and Lowe’s had a box of LONG, I should say VERY LONG, pop rivets. You need a rivet with almost 1/2″ grip to hold the skin, plastic, and backing. I installed the inside “rail” as an emergency repair and waited to do the cracks until I was home and had the shop handy.

I don’t know if this is a good repair or not. Without access to the back of the plastic, there is no way to put a washer on the rivets. Will they hold and will the plastic tolerate them? And will the Vulkem provide a seal? Don’t know, only time will tell.

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Forming the patches takes a bit of time if the cracks require patching up in the curve. This is particularly true if the crack is in the front radius, where a compound curve is required. All I can say is, you have to shrink the edge of the metal for the new patch before you put the bend in it. How much shrinking (thanks again, shrinker tool) and how much bending is pure esitimation, but I managed to luck out on the first try.

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What’s the bottom line, here? Check your wheel wells for two things. First, see if your banana skin is trimmed so that a tread can’t rip it. Second, the liner cracks probably exist, even if you haven’t had a tread separation. Run your hand along the liners to check them. Most of the cracks (all of the ones I’ve experienced) are in the outboard wall of the liners, so you can easily feel along that surface to find them.

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