In addition, tires will tell you if a problem exists with the original tire manufacturer or retreader for which warranty should be collected and solutions to the problem should be found.
The results of your examinations could enable you to assess the retreadability of different tire makes and models and lead to changes in maintenance procedures, tire specifications or fleet policies that enable your customer to get the most miles out of every tire and prevent a lot of problems before they happen.
Before coming to a diagnostic conclusion during any tire examination, it is vital that you examine the whole tire. Sometimes tires exhibit more than one condition and, frequently, the less obvious condition is the most important.
To make sure you don't overlook anything, get into the habit of inspecting tires the same way each time. Use a systematic approach just as your own physician does during your annual physical.
Start with the tread or crown area of the tire, then inspect the upper sidewall of the DOT code side followed by the lower sidewall and bead area. Then examine the opposite upper sidewall, lower sidewall and bead area.
Finally inspect the interior on the DOT code side and then the interior on the opposite side. You can change the order as you personally see fit, but make sure you do a complete examination the same way each time so you don't overlook anything.
Look for anything unusual. Remove all foreign objects from the tire. Take a probe from the black bag you are probably carrying and use it to determine the origin and extent of the 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 bead rubber and bead wires, look for cracked, burnt or brittle bead rubber, as well as swollen, distorted or deteriorated beads. Examine the innerliner for wrinkling or corrugations, blisters or bumps, cracks, looseness, color of the rubber and repair irregularities.
Circle each with a tire crayon so you can readily find them again.
Once you have located all the tire's symptoms and conditions, some clues to understanding the spectral language of tires speaking from the grave are as follows:
- Scuffs and abrasion — always look for scuff marks or abrasions around the suspect area. These are usually tipoffs that the condition was caused by an outside force.
- Smooth cut in the rubber — usually made by a foreign object
- Striations (furrows) in the rubber with chunks of rubber missing — usually indicates the rubber was pulled off the tire as a result of encountering a road hazard.
- Cracks (lines that are jagged) — occur from the inside of the tire out. They usually are a sign of separation. Separations always occur where two components are coming apart from each other.
- One low spot worn smooth in the tread, sometimes with a chunk of rubber missing — usually a result of air trapped under the tread.
- Smooth surfaces between components — indicates a separation; air trapped between the components will rub the upper and lower surfaces smooth.
- Rubber dust between the components — indicates the cords were rubbing against each other or the adjacent rubber; a separation of components that could be caused by outside elements such as rust or fatigue.
- Rust that travels along the cords (known as wicking) — 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 can rust even though nothing has penetrated the tire due to moisture permeation through the innerliner. In these cases the rust is generally spread out.
- Rubber that has a blue cast and perhaps a burnt rubber smell — indicates that the tire ran very hot and underinflated. If localized, it may indicate that the components in the area are separated due to excessive heat buildup.
- Scorched, brittle rubber (may have a blue cast) — usually found in the bead indicates the bead was exposed to high temperatures conducted by the wheel from the brake.
- Circumferential grooves cut or worn in the tread — a sign of spinning the tires on ice or snow. If the grooves are wide, this is usually a sign that the tire came into contact with an obstruction on the vehicle. (This can also be seen on the sidewall.)
- Soft, spongy or swollen rubber may also smell of oil or diesel — normally found in the sidewall and bead area is usually a sign of petroleum damage.
- Snags (damage that is irregularly shaped, jagged and usually accompanied by scuff marks) — indicate contact with a foreign object/road hazard.
- Straight crack extending from bead to bead in the interior of a radial tire — indicates an impact break.
- Ripped or broken belt (appears as a "rabbit ear") — sign of a radial tire impact break.
- Tattered or separated innerliner — usually a sign of running flat or severely underinflated.
- The most common cause of irregular wear and tire deaths is underinflation which can be caused by a variety of things including poor maintenance programs, improper mounting, leaking valve stems, etc. Misalignment is usually the second leading cause of irregular wear while service related conditions like penetrations, cuts and snags, and improper repairs, are commonly the second leading cause of tire fatalities.
The most comprehensive and expert resource for help in recognizing and determining out-of-service and irregular tire-wear conditions is the Technology & Maintenance Council's (TMC) Radial Tire Conditions Analysis Guide, which was updated last year to its fifth edition.
It provides more than 200 color photographs and illustrations and detailed descriptions of over 100 out-of-service conditions and 30 irregular wear conditions for both original and retreaded tires along with their causes and the actions that should be taken to prevent them. It is available in both book form and CD ROM from both TMC and the Tire Industry Association (TIA).
The best way to become proficient at analyzing and diagnosing tire failures is to do it frequently and expose yourself to as many types of tires and failures as possible. Repetition, that is, seeing the same tire conditions over and over again, is a sure fire way to learn to recognize them. The rest is elementary, my dear Watson.
Finally, when examining failed tires, use scrap tire forms or a mobile, web-based inspection tool to record your findings and generate crucial data for analyzing the fleet's problems. These forms are sometimes referred to as tire death certificates.
I once knew a maintenance manager of a fleet with really bad tire maintenance who was so honest with himself that on his "death certificates" under "cause of death/failure," he signed his name.
Please don't be this hard on any of your fleet accounts. Good bedside manners are vital at times like this.
Hopefully the pathological reports you derive from your tire autopsies will help your surviving patients live long, you and your fleet customer prosper, and your mother proud.