STRONGER CASINGS AND BETTER RETREAD TECHNOLOGY PUT A NEW FACE ON THE PROSPECT OF SECOND AND THIRD LIVES FOR TIRES
YOU’VE HEARD HORROR STORIES about retreads that failed.
These stories are normally told without an understanding of what makes tires, including new tires, come apart. They also often reflect a lack of knowledge about how good retreading technology actually is these days.
Tread will last, at most, about 350,000 miles, says Al Cohn, Goodyear’s manager of strategic initiatives for commercial tires. However, a properly maintained casing is designed to last as long as 750,000 miles, he says, and that’s why a careful retreading program has the potential to save money. Consequently, “Retreading is the solution to maximizing the investment that a fleet has made in the casing itself,” says Randy Clark, vice president of marketing for Michelin America Truck Tires.
“No major truck tire manufacturer would dream of bringing a truck tire to market that
has not been designed for multiple lives,” says Harvey Brodsky, managing director of the Tire Retread Information Bureau. “If manufacturers did, no one would buy it because it would not be cost-effective.” Cohn estimates that nearly 85 percent of large fleets retread their tires. “You can’t afford to put new tires on everything,” says Dorothy Maddox, vice president of Nick and Dees Trucking, a small fleet in Hereford, Texas. “You can’t afford to go any other way, because you can’t even sell the casings.” Her fleet’s experience with retreads has been spotty. On rare occasions, tread has peeled off, without a casing failure, and damaged their equipment. “Heat has a lot to do with the problems we’ve had,” she says, particularly during summer operations in the Southwest. She says the f leet’s present experience, with Michelin retreads, has been the best. They’ve had much better experience with retreading done by local dealers than with buying retreads on the road.
Maddox says casing preparation has proved to be a key to successful retreads, and experts agree that casing maintenance is the most important step for a retreading program. Because air is part of the structure of the tire, running underinflated will destroy a casing because it will flex more than it’s designed to, creating heat that weakens it.
Don Schauer, manager of fleet communications at Bandag, reports that 75 percent of on-road failures are the result of too little pressure for the load. Be careful about loading properly and, using pre-trip and onroad checks, keep tire pressures as close as possible to the maximum recommended pressure when fully loaded. Use a calibrated pressure gauge, not one that’s been bouncing around in the glovebox. Note tire damage likely to cause leakage and get repairs quickly.
The next step is to avoid abuse.
Round corners carefully so tires don’t run over curbs.
Avoid hitting objects on the road.
Correct repairs will preserve a good casing, while poor ones mean a death sentence. Bandag recommends having repairs done only by a technician certified by the Tire Industry Association.
Be aware that tires must be removed and installed with proper tools to avoid bead damage. (The old blow-it-onto-the-rimwith-ether trick is strictly taboo.) Unless punctures are sealed from inside the casing after removing the tire from the rim, tire cords will rust, rendering the casing useless.
Vocation also affects casing life. Pickup and delivery fleets may retread a number of times because treadwear is high; total miles on the casing will be less, however.
Schauer says it’s critical to track the age of the casing because rubber will eventually oxidize and deteriorate.
Many smart fleets put a five-year limit on a casing’s life to help guarantee its health until retired. Clark says trailer tires with relatively few miles may last a lot longer.
Even a quality retread needs to have the right tread pattern for the application, says Cohn. Consult a good tire expert who can help you pick the appropriate one.
Most linehaul fleets use good casings being retreaded for the first time (termed virgin casings) as drive tires. Cohn says a common pattern with Goodyears is to run a new tire 350,000 miles on a drive axle and then retread it for about 250,000 miles as a drive during the second life. A third life in the range of 100,000 to 150,000 can then be had on the trailer. Some casings, though, get terminally damaged and can’t be reused each retreading cycle. Visiting the retreader’s shop can help you know the quality of the work. The shop should have sophisticated, non-destructive inspection equipment that allows the technician to see inside the casing. Retreaders who warrant their work and have a reputation for backing it up (including paying for road calls) deserve your business. You can buy retreaded tires, but the long-term savings are greater if you preserve your investment in your own casings and have them retreaded. Industry sources estimate the cost of retreading your tire to be 30 percent or more of a new tire’s cost. If you have a good tire maintenance program, your
casings will perform more reliably than the average one you might buy from a dealer, and you’ll maximize the benefits you can get from a retreading program.
THE ART OF RETREADING
The retread process starts with careful examination of the casing. If an X-ray
or other technology determines it is defect-free, it is buffed down to ensure
an even diameter. This also produces a smooth surface for tight bonding of
the new rubber. After inspection, the casing receives any repairs required to
ensure that it has no defects caused by tread damage.
Finally, the job of restoring the tread begins. There are two basic methods:
Industry surveys have found most on-road tire remains were caused by failed casings, both from new tires and retreads, normally due to overload or low air pressure.
MOLD CURE. Uncured, soft-tread rubber is applied to the casing. The
casing is inserted into a large mold, or enclave, which contains the tread
pattern. The casing and raw rubber are subjected to heat and pressure,
which cures the rubber. Few retreads are done this way because a different
mold is needed for each tread pattern and tire size.
PRE-CURE. Pre-cured retreading, which accounts for 80 percent of retreading, bonds a strip of finished tread to the casing with less heat than is required for a mold cure. Advocates of this process argue that subjecting the casing to less heat means less risk of damage or deterioration. Pre-curing is done at 210 to 250 degrees, while mold curing is done at 295 to 310 degrees.
A cushion gum layer of uncured rubber is uniformly applied to the casing. A strip of tread with the desired pattern is then fitted around the casing, with its ends butting up against one another. The tire is put in a flexible envelope and pressure is applied inside an enclave to keep the tread firmly in place during the process. One size enclave does all sizes of tires. Heat, pressure and time cure the cushion gum and bond the tread to the tire.
Goodyear has a special form of pre-cure tread that has no seam across the
tire, says Tim Sawdey, manager of retread policy and supply. Called Unicircle, the tread is molded in a continuous ring rather than a strip. The tread is snapped onto the casing and is designed to hug the sidewall for better adhesion.
Once retreading is completed, another careful inspection must be performed. If the application of the new tread is not perfect, the job must be redone.
THE RETREAD PAYOFF
The cost of retreading a tire casing is 30 percent or more of the cost of a new tire, resulting in savings for an over-the-road operation of several hundred dollars per year per 18-wheeler, say retread experts.
2 SETS OF NEW TIRES FOR
TWO 350,000-MILE CYCLES
$350 x 36 tires
$12,600 –: 700,000 miles
= 1.80 CENTS PER MILE
1 SET OF NEW TIRES RETREADED
AFTER 350,000 MILES AND
RUN FOR 250,000 MILES
$350 x 18 tires
$6,300 x .30 (30% of new-tire cost)
TOTAL TIRE COSTS
$6,300 + $1,890
$8,190 -–: 600,000 miles
=1. 37 CENTS PER MILE
YEARLY SAVINGS WITH RETREADS
120,000 miles x .43 cents per mile (1.80-1.37 cpm)
GOODYEAR TIRE AND RUBBER
MICHELIN NORTH AMERICA
Smart Lifecycle Cost Control Can Help Fleets
Squeeze Every Last Mile Out of Every Casing
Here’s a bulletin for fleet maintenance managers responsible for extending tire casing life: If you start a serious tire inflation program today, you will enjoy a 10% improvement in tire mileage expectations tomorrow.
That’s only the beginning. If you add a proper tire rotation program, daily calibration of your tire pressure gauges, an alignment program and match up your duals to within 1/4-inch, you can expect the life span of your tire casings to improve by 30%. Of course, you can’t control all of your costs. Diesel fuel – pushing $3 a gallon – is just one example. So, your time is best spent focusing on the costs you can control – like tires. The industry average for roadside At the end of the day, the benefit is really not hard to understand. Putting it into action? Well, that’s another matter. downtime is 2.5 hours, and the number-one reason for that downtime is tires. With 18 tires on one vehicle, the odds are stacked against you. So, how can you improve the odds and, therefore, your lifecycle costs? For starters, underinflation still looms as the number-one reason for premature removal of a tire from service. Even though the tire industry has been preaching about underinflated tires for decades, the message falls woefully short. That’s too bad because underinflated tires mean nothing but trouble. Fuel economy goes down. Casing life drops dramatically. Removal miles, for the original tread and retreads, also go down. If your fleet runs tires that are 20% underinflated – 20 psi on a 100-psi-recommended pressure – for one year, expect removal mileage to drop 12% to 16%.Even though most fleets Know all of this, many maintenance programs still fall short. Inflation checks are an unpleasant, time-consuming task, to be sure. And, a yard packed with tractors and trailers is uninviting for even the greenest employee. Regularly scheduled checks multiply the problem. But, at more than $300 per new radial and $150 per retread, tires remain a major investment for any fleet. With today’s rising raw materials costs and resulting price increases – not to mention the high price of diesel – wringing every mile out of every tire should be a priority.
Inflation and Tire Life
Al Cohn, commercial truck tire technical marketing manager for Goodyear, says that most fleets don’t think about the consequences of underinflated tires. “These tires quickly develop a larger footprint than a properly inflated tire. That big footprint will ‘suck up’ tire-killing objects on the road like a vacuum cleaner. You can also expect significant irregular wear. If our job is to protect the original casing, we can, and must, do a lot better. “Let’s say that you’ve spec’d your new tires to run for 150,000 miles before removal,” says Cohn. “If you run those tires 10% underinflated, you’ll be down 10% in projected tire miles. That’s 15,000 miles right there. Not good. And, if you run your tires at 20% underinflation, you’ll be down in expected tread life about 12% or 14%,” Cohn says. In terms of retreadability, Cohn says running 30% underinflated drains 30% of the life out of a good radial casing. Another common issue, says Cohn, rests with how much air to put in a tire, when to put it in and at what ambient temperature. “Job one is to do your best to fill tires in a controlled temperature situation,” says Cohn. “Tiremakers like to talk about 100 psi at 60sF ambient temperature as an ideal starting point. “If you fill a tire to 100 psi at 60sF outdoors and wait a day before moving that tire, look at what can happen overnight. Let’s say the next day, temperature jumps to 100sF outside – the inflation pressure will jump to 110 psi just by sitting there. “The reverse is also true. If it’s 20sF the next day – which happens – your tire gauge will show there is only 90 psi in the tire,” Cohn claims. The lesson is basic, says Cohn: It’s important that inflation pressures are checked regularly.
Taking that a step further, Cohn says regularly calibrating tire gauges is a must. “But here’s the problem,” he says. “Let’s say the fleet shop has 10 guys, each with his own gauge. He’s got it taped up and contoured to his hand; it belongs to him. He may have had it for years. Now, if you ask all 10 guys to check the pressure in a tire that we know has been filled to 100 psi, guess what? You get 10 different readings, and some of them could be 12 psi off.” Ideally, inflation gauges should be Recalibrated daily. “This is especially critical for P&D fleets where you’re hitting curbs and running over a lot of debris,” Cohn says.
Another big contributor to lifecycle costs is tied directly to matching up duals. Mismatching duals happens often, and the taller tire – the one for the larger outside diameter – is forced to carry more of the load. As a result, that tire will wear out faster and more unevenly than its neighbour, not to mention the additional heat buildup the tire will suffer.And, the smaller-diameter dual next to it is being scrubbed and dragged along as it tries to make a revolution that matches up with its larger OD running mate. Both tires are going to miss their projected lifecycle costs by a lot.
“This is a bad situation,” says Cohn. “Make sure your duals are never more than 1/4-inch diameter different in OD. Some suggest 1/2-inch, but I say 1/4-inch.”
“We’re all in the chase for the millionmile casing,” says Guy Walenga, commercialtire engineering manager for Bridgestone/Firestone North American Tire (BFNAT), “but o get there, we must protect the original casing.” Walenga says he’s seen quite a few million-mile casings in his time, but most fleets won’t see such spectacular service. Whether your goal is a million miles or maximum lifecycle, how you get to that point depends on application and time spent in service.
With today’s rising raw materials costs and resulting price increases, wringing every mile out of every tire should be a priority.
“Secret number one is to make sure the new tires you buy are designed for retreadability,” he says. “The second ‘open secret’ is to place that new casing in line-haul service, on the steer axle, where it will rack up lots of miles very quickly. When you reach your pre-set removal miles for that casing, retread it, move it back to the drive axle and keep it in line-haul service.
Failing to rotate tires where there is a high discrepancy in wear between positions will lead to too-early scrapping.
Once again, you are going to pile up a lot of miles very quickly. “Since time and distance traveled are key to attaining the million-mile goal, once you place that casing on a trailer, it’s going to spend a lot of time sitting around,” says Walenga. “The casing ages, and the miles drop off.”
Alignment and rotation are probably the two most important service functions
in terms of preserving tire life and keeping costs down. Cohn says the number-one reason for regular truck alignments is to keep fleet drivers happy. “The second reason for aligning a new truck is tire mileage. When a fleet buys a new power unit, that vehicle will create a ‘set’ in its new tires, even if it has been factory aligned. Our advice is to check the alignment within 30,000 miles or 90 days. Check all the angles.” Interestingly, Cohn says one of the biggest problems facing fleet alignment today is the trailer. “Most fleets don’t own their own trailers. So, they don’t want to pay to have them aligned,” Cohn says. But an unserviced trailer will wiggle-waggle down the road, negating the work that’s been done on the tractor-tire program.
“You have to be running in a straight line to pick up that 30% gain in lifecycle cost,” adds Cohn. Another thing fleets talk about is tire rotation. Tires tend to wear more in certain positions, such as the front vs. the rear. Tires on tandem drive axles wear at different rates, depending on whether they are on the front or rear drive axle. Walenga notes that many fleets report the driver’s side steer tire tends to wear faster than the right side steer, not unlike passenger vehicles. Solution? If the driver’s side steer has 4/32nds or less remaining tread depth compared to the right-side steer, consider a left-to-right rotation. Failing to rotate tires where there is a high discrepancy in wear between positions will lead to too-early scrapping. “Some fleets don’t rotate because of the extra labor involved,” says Cohn. “But if their trucks are in for service anyway or a regular PM check, there’s enough value in tread and casing life to make tire rotation worthwhile.” Some fleets are using rib-type tires all the way around. What seems to work well is to run these tires for about 30,000 miles, then swap the steer pair with those on the left rear tandem. If an additional rotation is needed, the steers (previously the drives) can be swapped with the tires on the right rear tandem. For convenience, repaired tires can be placed on the front tandem. Even so, the most common type of rotation on the drive axle continues to be cross rotation, in which tires are swapped from one side to another, and those on tandems are also swapped between axles. As far as removal from service altogether, DOT standards for fleet removal miles are 4/32nds for steer axle tires and 2/32nds for both drive and trailer axle tires. But, Bandag’s Don Schauer doesn’t think fleets should wait that long. “We recommend tire removals at 4 to 5/32nds. This way, fleets can preserve casing life and experience fewer casing injuries.” Because many fleets are using very deep tread drive axle tires – 30/32nds or 32/32nds – they should consider moving a tire that’s approaching its removal mile mark back to the trailer. Then, when that tire is ready for retreading, move it back to the drive axle or leave it on the trailer.
New Way of Thinking
Somewhat new is the business of concentrating on a casing’s useful life “one 32nd at a time.” On average, “a casing in line-haul service should realize 15,000 miles per 32nd of tread depth,” says Cohn. “Every fleet is different, every driver is different, and every load is different, so it’s nearly impossible to make hard and fast lifecycle pronouncements.” To monitor tire lifecycle costs, a fleet or servicing dealer should purchase tire tracking software, available from most tire suppliers. These programs allow a dealer to track nearly every aspect of a tire’s life, from initial order through every retreading on to the scrap pile – and the resulting costs along the way.
Some fleets get seriously scientific when calculating costs and even consider vehicle duty cycle, road surfaces, climates and drivers. Certainly, if it were left up to accountants, fleets would buy the least expensive trucks and ride on the cheapest tires. But, real-world financial performance cannot be left to the low bidder. Having detailed lifecycle cost stats usually proves the accountants wrong. If an inexpensive tire comes with an early removal time and just one retread, it costs a great deal more than a more expensive tire with greater initial removal mileage that allows for multiple retreads. That’s why fleet operations people know that a less expensive tire may not be the best buy. Extending tire lifecycle cost is imperative to fleets that wish to remain competitive in their pricing while delivering freight on time. At the end of the day, the benefit is really not hard to understand. Putting it into action? Well, that’s another matter.
5things drivers can do to improve tire life
T i r e M a i n t e n a n c e
1. Maintain proper tire inflation pressure.
This is the No. 1 maintenance issue facing fleets today, regardless of the season. Underinflation leads to increased tire deflection, which leads to increased heat. Heat is a tire’s worst enemy. Low inflation leads to reduced tire miles, reduced retreadability, poor fuel economy and even an increase in the number of punctures.
Check your tires at least weekly with a calibrated air pressure gauge.
2. Fingertip diagnostics.
Running your hand across the tread surface can identify alignment-related wear conditions. For example, if you run your hand across the tread surface and you feel a “stepped” wear pattern (not smooth), you probably have a vehicle toe-in condition. Catching alignment wear conditions early will allow the truck to be corrected so the tire can still achieve high removal miles. A Goodyear dealer can professionally check your alignment.
3. Visual tire inspection.
Look for signs of sidewall damage and tread area punctures.
4. Train drivers and mechanics .
Work with your tire professional, who can conduct seminars on basic tire maintenance. Once drivers understand that tires are the highest fleet cost next to fuel, tires become a lot more important. Anything you can do to protect that investment is critical.
5. Don’t exceed tread depth standards.
Depending on your specific service vocation, make sure your fleet does not exceed removal tread depth standards. If you see a significant amount of off-road service, you may be best served to ensure you have enough remaining rubber before retreading to make sure the casing is protected against stone damage and stone drilling.
YOUR TIRE MAINTENANCE CHECKLIST
Under inflation is the leading cause of tire failure. It results in unnecessary tire stress, irregular wear, loss of control and accidents. A tire can lose up to half of its air pressure and not appear to be flat!
It’s important to have the proper air pressure in your tires, as under inflation is the leading cause of tire failure. The “right amount” of air for your tires is specified by the vehicle manufacturer and is shown on the vehicle door edge, door post, glove box door or fuel door.
It is also listed in the owner’s manual.
1. When you check the air pressure, make sure the tires are cool — meaning they are not hot from driving even a mile. (NOTE: If you have to drive a distance to get air, check and record the tire pressure first and add the appropriate air pressure when you get to the pump. It is normal for tires to heat up and the air pressure inside to go up as you drive. Never “bleed” or reduce air pressure when tires are hot.)
2. Remove the cap from the valve on one tire.
3. Firmly press a tire gauge onto the valve.
4. Add air to achieve recommended air pressure.
5. If you overfill the tire, release air by pushing on the metal stem in the center of the valve with a fingernail or the tip of a pen. Then recheck the pressure with your tire gauge.
6. Replace the valve cap.
7. Repeat with each tire, including the spare. (NOTE: Some spare tires require
higher inflation pressure.)
8. Visually inspect the tires to make sure there are no nails or other objects
embedded that could poke a hole in the tire and cause an air leak.
9. Check the sidewalls to make sure there are no gouges, cuts, bulges or other
irregularities. NOTE: Air pressure in a tire goes up (in warm weather) or down (in cold weather) 1-2 pounds for every 10 degrees of temperature change.
A bad jolt from hitting a curb or pothole can throw your front end out of alignment and damage your tires. Have a tire dealer check the alignment periodically to ensure that your car is properly aligned. Misalignment of wheels in the front or rear can cause uneven and rapid treadwear and should be corrected by a tire dealer. Front-wheel-drive vehicles, and those with independent rear suspension, require alignment of all four wheels. Have your alignment checked periodically as specified by the vehicles’ owners manual or whenever you have an indication of trouble such as “pulling” or vibration. Also have your tire balance checked periodically. An unbalanced tire and wheel assembly may result in irregular wear.
Regularly rotating your vehicle’s tires will help you achieve more uniform wear. Unless your vehicle’s owners manual has a specific recommendation, the guideline for tire rotation is approximately every 6,000 miles. Sometimes irregular tire wear can be corrected by rotating your tires. Consult your vehicle’s owners manual, the tire manufacturer or your tire dealer for the appropriate rotation pattern for your vehicle. NOTE: If your tires show uneven wear, ask your tire dealer to check for and correct any misalignment, imbalance or other mechanical problem involved before rotation. Before rotating your tires, always refer to your car’s owner's manual for rotation recommendations. If no rotation period is specified, tires should be rotated approximately every 6,000 miles
Advanced and unusual wear can reduce the ability of tread to grip the road in adverse conditions. Visually check your tires for uneven wear, looking for high and low areas or unusually smooth areas. Also check for signs of damage. Tires must be replaced when the tread is worn down to 1/16 of an inch in order to prevent skidding and hydroplaning. An easy test: place a penny into a tread groove. If part of Lincoln’s head is covered by the tread, you’re driving with the proper amount of tread. If you can see all of his head, you should buy a new tire. Built-in treadwear indicators, or “wear bars,” which look like narrow strips of smooth rubber across the tread will Appear on the tire when the tread is worn down to one-sixteenth of an inch. When you see these “wear bars,” the tire is worn out and should be replaced.
Visually check your tires for signs of uneven wear. You may have irregular tread wear if there are high and low areas or unusually smooth areas. Consult your tire dealer as soon as possible.
OTHER IMPORTANT INFO…
ABOUT HOW TO TAKE CARE
OF YOUR TIRES
Proper tire care and safety is simple and easy. The Rubber Manufacturers Association (RMA) recommends getting in the habit of taking five minutes every month to check your tires, including the spare.
Practice good driving habits, which will help keep your tires in good condition.
• Obey posted speed limits.
• Avoid fast starts, stops and turns.
• Avoid potholes and other objects on the road.
• Do not run over curbs or hit your tires against the curb when parking.
• Do not overload your vehicle. Check your vehicle’s tire information or owners manual for the maximum recommended load for your vehicle.
If properly cared for, tires can last a long time — usually from 40,000 to 80,000
miles, depending on the application.
TIPS ON DRIVER SAFETY
It’s important to know how different weather conditions affect your tires and your car, no matter the climate in which you’re driving.
April showers can bring pretty flowers as well as dented fenders.
According to National Highway Traffic Safety Administration statistics, nearly one million vehicle accidents a year occur in wet weather. Many of these rainy-day wrecks are caused by motorists failing to appreciate the vast difference between driving in wet and dry conditions.
To drive safely on wet pavement, you have to recognize the demands that you, your vehicle and your tires face. It’s very different than driving on dry pavement, but many motorists fail to change techniques and attention. That’s when many wet weather accidents occur.
Wet weather driving tips include:
• Slow down. You reduce the risk of hydroplaning should you run into deeper water puddled on the road. Wet weather also affects your brakes, so you need to drive slower in these conditions.
• Maintain a safe distance. Even with a good wet weather tire, be prepared for longer stopping distances on wet pavement. Since other cars may not have proper tires for wet weather driving, be extra alert at stop signs and red lights.
• Choose tires carefully. Too many drivers buy a tire based on initial price or appearance. For optimum performance in the rain, select a tire with tread design and rubber compounds that provide enhanced wet weather driving capabilities.
• Properly maintain your tires. No tire can provide good wet traction once the tread is worn below 2/32nd’s of an inch (0.16cm) tread depth. Check your tires regularly and replace them at the proper time. Also, maintain the proper air pressure in your tires; check your vehicle manufacturer’s handbook or the door jamb for the proper air pressure for your particular vehicle and tires.
• Go smoothly. When braking, accelerating or turning, avoid jerky, abrupt movements.
• Avoid hydroplaning. If you feel your vehicle starting to hydroplane (riding on the surface of the water), take your foot off the accelerator— and don’t hit your brakes. If you have a manual transmission, it may be necessary to depress the clutch petal and reduce gear; then re-engage the clutch after you gain control.
• Plan your braking. If you are entering a curve, slow down and brake gently before you start to turn.
• Turn on your lights. In most states, it’s required by law when it’s raining. It will help other drivers see you.
• Check your wipers. Install new wiper blades at least once a year to ensure good vision.
These tips can be shortened to “T & T.”
Think and Tires. Think about your driving and install good tires for wet weather. Once you’ve installed the tires, keep them inflated properly and replace them when tread-wear indicator bars show. Don’t be shy about asking for information from your tire dealer.
Your safety—could depend on your tires and how you think.