Retreads & Rejects

Want answers about how you can better manage your tire costs? Turn to your scrap pile. Old tires will speak volumes about your fleet’s maintenance practices or if you’ve made a mistake with your spec. They can also tell you if tires are being scrapped needlessly rather than repaired and/or retread, or if a problem exists with the original tire manufacturer or retreader for which warranty claims should be filed and solutions found.

During any tire analysis, it is vital to examine the whole tire. To make sure you don’t overlook anything, inspect tires exactly the same way each time. Use a systematic approach to inspect the crown, sidewalls, bead areas, and interior of both sides of the tire.

Remove all foreign objects. Use a probe to determine the origin and extent of damage or condition. Look for punctures, cuts, distortions, or worn areas in the tread. The sidewalls may have cracks, bulges, soft and spongy rubber, weather checking, cuts, snags, and separations. Check the beads for damage to the rubber and wires, look for cracked or brittle rubber, as well as swollen, distorted, or deteriorated beads. Examine the innerliner for wrinkling or corrugations, blisters or bumps, cracks, looseness, and repair irregularities.

Once you note all symptoms and conditions, the following list can help in diagnosing causes:

> If you see tread damage, note where you see it. If it’s evident in the centre of the tire but not on the shoulders, the tire was likely run overinflated. If the damage is noticeable on the shoulders but not in the centre, the tire was probably run underinflated.

> Circumferential grooves cut or worn in the tread indicate tires spun on ice or snow. If the grooves are wide, this is a sign that the tire came into contact with an obstruction on the vehicle. (This can also be seen on the sidewall.)

> Smooth cuts in the rubber are usually caused by a foreign object.

> Striations in the rubber with chunks of rubber missing indicate the rubber was ripped off the tire by a road hazard.

> Smooth surfaces between components of the tire indicate a separation; air trapped between the components will rub the upper and lower surfaces smooth.

> Rubber dust between the components indicates a separation caused by rust or fatigue; the cords will rub against each other or the adjacent rubber.

> Rust that travels along the cords is usually caused by an outside penetration that allowed moisture and air into the tire at a specific location. However, as some tires age, the steel cords rust even though nothing has penetrated them. In these cases the rust generally spreads.

> Rubber that has a blue cast and perhaps a burnt rubber smell indicates the tire ran very hot. Quite possibly, components in the area separated due to excessive heat buildup.

> Scorched, brittle rubber — which may have a blue cast and is usually found in the bead — indicates the bead was exposed to high temperatures conducted from the brake.

> Soft, spongy, or swelled rubber, which may also smell of oil or diesel) is sometimes found in the sidewall and bead area. It’s a sign of petroleum damage.

> Snags (damage that is irregularly shaped, jagged, and usually accompanied by scuffmarks) indicate contact with a foreign object.

> A straight crack extending across the crown in the interior of a radial tire indicates an impact break.

> A ripped or broken belt (appears as a “rabbit ear”) also indicates an impact break.

> Tattered or separated innerliner is a sign that the tire was run flat or severely underinflated.

Conducting an examination of your failed tires is the easy part. The real work is in putting your findings to good use. As you take a hard look at your worn-out tires, write down what you see (create a form, so your records will be consistent.

Now you can begin to look at what the wear patterns on tires in your scrap heap say about your tire management practices. Dead tires, after all, really do tell tales.