How long can you make those casings last?

Making the right casing utilization decisions

The three most frequently posed questions concerning
tire casings are:
• Which new tire manufacturer makes the best casing for retreading?
• How many times can you safely retread a casing?
• What age limit should you put on casings?

When Bandag suggests casing specifications for a fleet, we try to learn as much about the fleet as possible to understand their specific application requirements. Knowledge of wear rates, trade cycles, average trip range, and the likelihood of tire damage, can help you determine an acceptable service level that keeps downtime and costs to a minimum.

Let’s start with the first question.
Which new tire manufacturer makes the best casing for retreading?

Several years ago, you might have checked The Tire Retreading/ Repair Journal, a publication of the International Tire and Rubber Association (ITRA), which has since become the Tire Industry Association.

ITRA annually surveyed fleets and retreaders in an attempt to find the most retreadable casing. Several years ago, they came to the conclusion that the survey was not scientific and really amounted to a popularity contest. The fleets that did respond to the survey would list the new tire brand they used most as the most retreadable casing. The same was true of the retread manufacturing dealer side of the survey. Their votes generally went to the brand of new tire that represented the largest percentage of their sales.

The ITRA actually stopped conducting the survey several years ago. That hasn’t changed the fact that many fleet managers and executives still want to know how to make the best choice when making that substantial investment in new tires. Some brands obviously differ in casing durability, but brand name alone is not sufficient.

Most tire manufacturers produce high quality commercial truck tires that are very suitable for retreading. The better known tire manufacturers have invested in design technology, and use top quality rubber and steel. Many have also worked to achieve ISO certification of their manufacturing processes, showing a real commitment to the management of quality control. These capabilities allow them to repeatably manufacture quality retreadable
casings. Many suppliers offer warranties covering casing life or retreadability. Knowledge of your tire supplier’s warranty programs and capabilities will help you to make good choices.

What you really want to do before making that new tire purchase decision is to consider tires as valuable fleet assets that are worth maintaining. If you do that, and support and manage those assets with a good air pressure maintenance program, you will probably opt for the quality brands rather than bargain basement prices. Making that right decision will result in getting you the best
possible return on your tire investment … and less unscheduled downtime.

How many times can you safely retread a casing?

I find this to be an application specific question

On the vocational side, including waste haulers, tires generally have a short tread wear life. The tread on a new drive tire can be worn off in 30 to 45 days. Due to fast wear, steer axles of local waste hauler trucks may even be a good position for some sizes of retreaded tires. If that is the kind of hauling you are involved in, you might retread your casings 4, 5, or even 6 times, should they last that long in the hostile environment which includes neighborhood curbs and severe landfill punctures.

A longhaul, over-the-road fleet, on the other hand, might get many miles from their steer and drive tires before they are ready to be retreaded. By the time a tire is ready to be retreaded the first time, it may already be three years old or more. If the tire passes all retread inspection criteria and non-destructive testing, a second retread can usually be done if the effect of aging is just cosmetic.

Other factors, like trade cycles could also impact the number
of times a casing is retreaded. Typically, in regional fleets, tire casings are retreaded two or three times. Drive and steer tires wear quickly in regional pickup & delivery or LTL applications. This leaves plenty of casing life for both drive and trailer retreading, so second and third retreads can be used successfully. Again, a casing’s retreadability is always dependent on maintaining correct air pressures.

What age limit should you put on casings?

This is another question that can’t be answered without giving consideration to the application that the tire will be used in.

Tires age at different rates depending on running temperatures, exposure to sunlight, and the stresses they have absorbed in use. Proper inflation is critical to keeping temperatures low, so the aging process can be slowed.

We have found when fleets have had severe enroute tire failure problems, those problems are often accompanied by pushing the age limit on casings a bit further than they should have. In some instances, we have seen casings 13 to 16 years of age running in a fleet. Your own routes and loads will probably put a bit more stress on your tires. The chances of damage from these stresses increase over time, so age can be a useful measurement.

Sometimes an LTL or TL fleet manager will take drastic steps to reduce the enroute failure problem and reduce his age limit on casings to 3 or 4 years. While he will usually see dramatic results with such an action, especially when combined with dry air inflation and routine pressure checks, he may not be realizing the optimum return on his casing investment.

If he would move to a 5 to 6 year age limitation, with a strong air pressure maintenance program, he could get a better return on his casing assets without increasing his exposure to enroute failures.

Some waste hauler fleets have been successful with age limits of up to 8 years for local-use drive tires. At that age, tires are usually heading toward the scrap pile, but a good yard check program, including inspections and air-ups, can keep tires in great shape.

Another factor to consider when setting those age limits is modern technology. With equipment like the 7400 Insight Casing Analyzer, which uses shearographic lasers to perform a bead-to-bead inspection scan, a trained inspector can tell much more about a tire. He can see if there has been damage to the structure of the casing beyond the simple effects of age. This means that casings are more accurately sorted for retreadability, helping your tire ROI. Bandag dealers continually invest in capabilities to offer the best inspection technology.

The bottom line is, that simply knowing the age of a casing is not enough to justify scrapping it. Trained casing inspectors and new inspection tools are available to help you make better decisions.

Solutions for Today and Tomorrow

By now, you have probably come to the conclusion that there are no silver bullets for these three questions. However, working with a quality supplier to help you track the data necessary to make good business decisions can go a long way in making those right casing purchase and management decisions. Air pressure maintenance, yard checks, and shearographic inspection will get you the longest possible use from your tire assets.

Depending on the size of your fleet, you have the additional option of outsourcing your tire management headaches. When you outsource, you are guaranteed a consistent level of performance at a consistent price, and the tire experts get to worry about making the right casing decisions while delivering the agreed level of performance.

— Eugene Johnston, Manager, Process Development, for Bandag’s Innovation Core Process.

Reprinted with permission
Bandagram magazine, Bandag, Incorporated, © 2004