MONTREAL, Que. — Tires are a fleet’s third-highest operating expense, just after wages and fuel. But while many fleet managers can tell you precisely how many drops of diesel they burn, tire life is often described in vague terms, says Lorenzo Borella, general manager of Montreal’s Système de rechapage RTS.

A closer look at the life of rolling rubber will identify just how quickly the rolling rubber is heading to the scrap heap, and stress the need to maximize the underlying investments.

Having a healthy casing retreaded, for example, can save as much as 50% compared to buying a new tire of the same brand and model. According to the Tire Retread Information Bureau, those savings add up to billions each year in the North American trucking industry, says Robert Palmer, director of market sales for Bridgestone Americas tire operations.

Under pressure

To keep casings in good shape and suitable for multiple retreads, the first step is to maintain correct tire pressures. So measurements based on a quality gauge should even be part of the pre-trip inspection, suggests Palmer.

“Underinflation in particular can be detrimental to casings, since this condition causes casings to flex as they roll under loads, which can result in heat,” adds Mahesh Kavaturu, marketing manager at Goodyear.

Granted, removing valve caps one by one and checking each tire’s pressure takes time, which costs money, says RTS’ Borella. But the effort will pay in the long run if you save thousands on tires and avoid unpredicted downtime.

Hitting tires with a hammer is better than nothing, but it will only tell you whether a tire is completely flat or not. “The hammer can’t tell the difference between a tire at 80 and another one at 85 psi,” Borella says.

Neil MacDougall, service manager at Don Anderson Haulage in Gormley, Ont., stresses the importance of ensuring a tire program includes the people who work behind the wheel. “The way I look at it, every one of my drivers is one of my technicians, and we use our drivers to do their due diligence of pre-trips, post-trips, and report any issues with any part of our trailers — not only the tires,” says the over-dimensional carrier’s maintenance expert.

This way, drivers become living data sources, and they are paid accordingly. “We give them a little incentive to help us. There is a safety bonus involved with our company, so if a fellow has a flat tire because it was flat and he didn’t report it … it’s a deduction off of his annual safety bonus,” MacDougall says.

Phil Boarts, Michelin Truck Tires’ product category manager – retreads, agrees that drivers have a vital role to play in preventing tire damage. “Fleets should always have a good written maintenance policy in place to specify the practices they want followed. Driver training and pre-trip inspections are a critical step for tire and casing health and longevity,” he says.

Hands-on demonstrations showcasing the damage from curbing and road hazards will help drivers understand the issues, adds Bandag’s Palmer.

If you’re the person responsible for buying tires, it’s also important to beware of deals that seem too good to be true. Often they are that very thing. Lesser-quality tires can be offered at a low purchase price, but wear away significantly faster than their counterparts.

Neil MacDougall tried some of the low-cost rubber, but got four times more mileage with the Michelins or Continentals he normally spec’s. Now he says he’d rather use his own retreaded quality casings than brand new tires from a cheap brand.

Mismatches and rotation

Unless you use wide-base singles, mismatches in a dual assembly are another threat to casing integrity. Tires that are different – by position type, brand, or degree of wear – but still matched together will cause one to work harder than the other, accelerating wear and limiting the potential of retreading.

In an ideal world, tires in a dual assembly should be matched by brand and model, says Borella. Each tire manufacturer has its own “recipe” and sidewall flexing range. So mixing different brand of casings, even if perfectly retreaded, will result in an imbalanced workload. The same issue will arise if there’s a mismatched tread depth.

“Normally, tires run pretty close in tread depth when they’re matched per duals. But there are times when somebody will have a flat, and they’ll change the tire, and they’ll put a used tire on, and it may not be exactly matched up. So the next time we come up for service, we’ll try and match those tread depths up within 3/32nds,” says Don Anderson Haulage’s service manager.

Also keep in mind that load and wear on tires will vary between drive and trailer tires, which is why tire rotation is so important. As most modern tires are directional, rotating in a criss-cross pattern is no longer such a good idea. It’s better to stick with front-to-back rotations.

“If you have a tandem-axle trailer for instance, [let’s say] the front axle is 10/32nds and the rear axle is 7/32nds. You want to rotate those tires so that you put the highest tread depth on the rear,” advises MacDougall. “When any tandem turns, there’s a little bit of scuffing that occurs. So if you put the higher tread depth on the rear, then it reduces that scuff. If the higher tread depth was on the front, then it would act as a pivot, and the rear axle would scuff more. All the little things add up on the bottom line.”

Timing and frequency

To get the most out of every tire, the goal is to remove the tire late enough in its life to take full advantage of the current tread — but not too late. Waiting too long could increase the threat of a casing being damaged by stone drilling. It’s a balancing act, and there’s no single answer to decide when to remove a tire for retreading, or the number of times a casing can be retreaded.

It all depends on the application. The terrain and routes, driving habits, fifth wheel positioning, season, even the brand of vehicle — as engine torque and suspension calibration vary — can be deciding factors.

Many fleets remove tires for retreading when they reach 4/32nds to 6/32nds of an inch, our experts agree. In case of doubt, your retreader of choice can offer sound advice.

The number of times a casing can be retreaded also depends on the life it has led. In application such as refuse or construction, for instance, tires can be retreaded as often as every 30 to 45 days. “When doing local hauling with a lot of stop and go, there’s little heat generated, so the casing isn’t really put to the test. On the other hand, the tread wears much faster in such an application,” says Borella.

On long-distance applications, some fleets will allow one or two retreadings at the most, while it’s not unusual to see tires retreaded three times in regional operations. Once again, good judgement is the key, since many factors can shorten a casing’s life:

• The more often a tire is mounted and dismounted, the more the bead – the area where the tire “sits” on the rim — can be damaged by installation tools.
• Exposure to the sun can create cracks on sidewalls over time.
• Exceeding the manufacturer’s recommended speed limit – which may be lower than posted speed limits – can cause a tire assembly to overheat.
• Presence of moisture in the tire will corrode the steel belts over time.
• Trucks and trailers sitting idle for long periods of time put all the weight and stress on the same area of a casing, which can cause premature damage.

Save money, gain trust

While retreading a tire is a means of saving money, there are ways to stretch every tire penny even more. Keep a close eye on your annual casings’ reject rates, and use them as key performance indicators to identify trends such as troublesome driving habits or tire brands.

Take a few seconds to organize and mark your used tires by brand and wear level. That will avoid mismatches and tires being shipped for retreading while there’s still good mileage in them.

And arrange for your retreader to handle the inventory burden. Most will accept that kind of deal, especially if you’re a good customer. In fact, mutual trust is an important part of a carrier-retreader business relationship. A carrier can do due diligence and inspect tires looking for cracks, bulges, cuts, or other signs of aging, but only a retreader has the sophisticated equipment to establish a tire’s true health.

“The dealer that we use, we’ve been using for nearly 20 years, and I have the same tire man come and do all my tires. Every week he’s here. And if he can’t come, then I will wait for the next week when he can come,” says MacDougall. “He knows what I’m looking for, and he will do a visual inspection and then if he says the casing is scrap, I have no issues. I trust him 100%.”

The changing tech of tire retreading

The basic method of retreading tires hasn’t changed that radically on the surface. Look a little deeper, though, and there is plenty of new technology involved. Materials have evolved to include new rubber compounds, belt assemblies, and seamless ring-like tread belts.

Ever-evolving traceability ensures that retreads are actually built from your own casings, and can inform every step of the rejuvenation process. Sophisticated shearography inspection tools help decide if a casing is suitable for retreading, and also tell a story about your tire use — offering charts and graphs extrapolated from the scanned data.

One of the biggest game changers of all remains the automation of the buffing process, which can ensure a uniform surface for retreading. Unlike a human worker, machines don’t feel fatigue, and are not distracted. Automation brings the customer the same casing preparation quality, regardless of the time of day or who is working a particular shift.