November/December 2013
Solid tires can keep scrap-handling equipment up and running when air-filled tires would have left it down for the count. Get the longest life from your tires by selecting the right design for your equipment and operating conditions.
By Ellen Ryan
Solid tires are on a roll. Sales of such tires have been trending upward for a range of equipment, from compact skid-steers to large wheel loaders, according to both sellers and manufacturers. They attribute the tires’ popularity in the recycling industry in part to the super-sizing of scrap-handling machines: As the equipment gets larger and the demands heavier, solids are more often up to the job. The stakes are high because tire problems can translate to slower production, diminished efficiency, and lost revenue. That’s why solid tires, with their durability and hardiness in harsh conditions, are so important, and it’s why more recyclers are “realizing the value” of solids even though they’re more expensive than pneumatic and foam-filled options, one solid-tire salesman says.
Aside from their cost, solid tires have a few other drawbacks, too. They provide a rougher ride, create more wear and tear on the base machine, and they’re heavier, which drags down the available horsepower. Sharp scrap on the ground can cut or chunk them, shortening their life and further compromising the ride, and potentially damaging heat can build up inside them, especially if the machine moves too fast, runs too long, or turns tightly in confined spaces. Those cons aside, solid tires deliver the solid performance recyclers need to avoid downtime, which trumps most other considerations. To make your solid-tire shopping a bit less tiring, keep the following factors in mind.
Asking the Right Questions
The working conditions of the base machine are the most important factors to consider in selecting solid tires over pneumatic or foam-filled tires and in choosing the right solid tire design for a specific piece of equipment. “It’s critical to understand how tires are used in the application,” says Mike Dembe, market development manager, North America–construction for Camoplast Solideal (Charlotte, N.C.). “Factors such as speed, length of run, surface conditions, loading characteristics, and other factors can impact tire performance and longevity greatly and must be considered before selecting a tire solution.” For each tire purchase, consider these variables:
Operator. How does the operator run the equipment? Does the person speed, make frequent turns, or otherwise handle the machine roughly? Or is the operator careful, deliberate, and conscientious? The latter can extend the life of the tire significantly.
Load and carry demands. “Your supplier should be able to present load and carry data, detailing how much load and what speed their tire can be expected to withstand,” says Buck Hill, owner of Setco Solid Tire & Rim Assembly (Idabel, Okla.). These considerations can include how much ground pressure a particular load will exert, how much horsepower per tire an application requires, and how much deflection there will be under a certain load.
Yard conditions. What are the conditions in the yard? Is it paved and kept clean, or is it oily, uneven, and littered with sharp debris? Although sharp debris will not put a solid tire out of commission as it might a pneumatic tire, it can damage the tire surface.
Environment. In what elements will the tires operate? Environmental conditions such as ice, snow, and mud—and whether the base machine is used indoors, outdoors, or both—should determine whether smooth or treaded tires are preferable.
Schedule. Does the equipment run one shift, two shifts, or 24/7? Do the tires have a chance to cool during operation or between shifts? Some solid-tire designs dissipate heat buildup better than others.
Maintenance. How diligently are the tires inspected for wear and damage? How often are they rotated?
Getting Below the Surface
When selecting solid tires, it helps to know a bit about their composition. In general, solid-tire manufacturers start with natural rubber and add varying amounts of fiber, silicone, and other elements for durability and strength, plus carbon black (without it, the rubber would be yellow-beige). Manufacturers use natural rubber—or a formulation as close to natural rubber as possible—because it resists the heat that builds up in that much mass under pressure.
Over the years, manufacturers have adapted their rubber formulas to address common problems. In the early 2000s, for example, solid tires used in scrapyards would wear out from chunking, says Bob Gilkenson, president and owner of Solid Boss Worldwide (South Haven, Mich.). “To work with scrap applications, I realized we needed more elastic compounding,” he says. “That doesn’t necessarily avoid a slice, but rubber that stretches more chunks less.” Polar Rubber Products (Oshawa, Ontario) has “found a compound that cures slower, offering more consistent wear throughout the tire,” says Jason Greenham, sales manager. “We’ve gotten 20 percent more wear out of the inner part of our two-tier tires, which makes them more retreadable, lowers the cost of ownership 30 percent, and lowers the amount going into landfills.” Setco has developed a heat-dissipating compound for tires used on larger loaders, which have more heat-related tire problems than smaller machines due to the greater weight and pressure on the tires, Hill says.
Synthetic-rubber solid tires generally cost less than tires made of natural rubber and tend to function best in less-demanding operations, says Bob McGlasson, general sales manager of TY Cushion Tire (Ontario, Calif.), which sells synthetics. Like their competitors on the natural-rubber side, manufacturers of synthetic solid tires have had to tinker with their formulas to meet certain scrap-industry demands, such as the growing size and weight of scrap-handling equipment. They couldn’t just make their tires larger and larger because “the pneumatic rim determines the size of the tire,” McGlasson says, so “we had to change our compounds for heavier load ratings.” Although synthetics are more durable than they were in the past, he admits they aren’t designed to handle around-the-clock operation.
Manufacturers also offer tire formulas and designs for special needs. For instance, scrapyards can order tires with customized rubber formulas for some oil or acid resistance, though sellers emphasize the word some. If oil resistance is a concern, natural rubber is the better choice, says Bennie McGill, Setco’s Midwest regional salesman. “Synthetics are made from oil, so encountering oil will mean an ooey-gooey mess.”
A Hard Day’s Ride
Advances in rubber formulas have improved the ride quality of solid tires, too, these tire makers and tire sellers say. Dembe explains approximate differences in ride quality by benchmarking against the softest option, a radial pneumatic loader tire, assigning it a rating of 100 for the best ride quality. In comparison, depending on the surface conditions and the tire’s inflation, a bias-ply pneumatic tire might rate 90 to 95; a foam-filled pneumatic tire, about 80 to 85; a solid tire with apertures (more on these later), about 80; and a plain solid tire, 70 to 75. Recognizing solid tires’ shortcomings in the comfy-ride department, manufacturers have tried to make them more like car tires to avoid rattling both the machine and the operator. The trouble, McGill says, is that “machines are getting bigger and heavier, but the softer the tire, the less load it’ll carry.” Setco’s Hill says customers ask him why he would recommend a tire with anything less than the greatest load capacity. “The quick and easy answer is ride and price,” he says, explaining that a tire with the highest load capacity won’t give the best ride, but a tire with the best ride won’t have the greatest load capacity. “The trick,” he says, “is knowing the application and getting the right tire.” (See “Tire Shopping Suggestions” on page 92 for tips on buying solid tires.)
Manufacturers have approached the challenges of tire cushioning and capacity in two ways, with the solution determined, in part, by the tire design. Scrap-industry equipment uses two principal types of solid tires: those cured onto an expanded wheel and those pressed onto a pneumatic-shaped wheel. The former often are found on larger equipment, the latter on forklifts or skid-steer loaders. Users will notice a smoother ride with the pneumatic-shaped wheel, Gilkenson says, because tire makers are now using two different tiers of rubber—a softer inner layer and a harder outer layer—for a more cushioned effect. “Press-ons have a soft inner core with steel bands around the circle that keep the tire from spinning free of that rim,” says Bob Bedard, manager of NASCO-OP (New Philadelphia, Ohio). “It’s a very popular option for smaller equipment.” At least one company now offers a press-on tire for a bigger machine, such as a front-end loader.
The other approach to improving the ride is to add apertures—holes measuring about ¾ inch to 2 inches in diameter—through the sides of a solid tire. Manufacturers create these openings by inserting heated probes into the rubber, which raises the internal temperature quickly to cure the tire fast and help lower production costs, Gilkenson says. Their main benefit is improving ride comfort: “Before apertures, [riding on] solid tires used to be like riding on a stagecoach,” says Dan Soley, executive vice president of sales and marketing for Miller-Bradford & Risberg (Sussex, Wis.). But apertures also help dissipate heat and reduce machine wear by providing a more cushioned ride, which reduces shocks back into the machine’s driveline.
Apertures do have a few drawbacks: They reduce a solid tire’s load capacity and can increase heat buildup due to the constant flexing of the rubber. “A tremendous amount of heat is generated from the flex, and then the rubber breaks,” Hill says. Also, a tire without apertures can be used until it’s worn down nearly to the rim; one with them cannot. In addition, hardness allows a tire to wear longer, and apertures reduce a tire’s hardness level.
Setco has patented a process to punctuate a solid tire with a large number of ½-inch holes it calls vents. “Lots of little holes, evenly spaced throughout the entire tire, create less heat,” Hill says. An extreme-load-capacity tire from the company uses a combination of vents and a new rubber compound that’s mechanically reinforced to flex less. “The small holes flex very little but instead vent the internal heat that’s generated from extreme loads and continuous cycles,” he says.
The Cost-Versus-Price Equation
For solid-tire manufacturers, the market has become more competitive since the mid-2000s, Gilkenson says. As the prices of raw materials such as rubber and oil started rising, more competitors—especially from Asia—started entering the niche. “Ten years ago we had two competitors; now we have 15,” says one solid-tire seller. “A dealer we had had for years—a dealer, not a manufacturer—can now beat our price. He went to Asia and made his own deal.”
When the economy crashed in 2008, raw material prices—and, hence, solid-tire prices—declined, but not nearly as much as they’d gone up. Now prices have plateaued. What does that mean for scrap recyclers? It gives them options. Solid tires can be expensive, but Soley notes that prices have come down to the point where “smaller companies with smaller budgets” can afford them.
The bigger point sellers and manufacturers want to make is that solid tires’ longer life can justify their higher price compared with other tire choices. Various sources say a solid tire has a life span two to three times that of a pneumatic tire. If new tires and rims for a skid-steer are $3,000 for pneumatics and $5,000 for solids, Soley says, and “a very, very conservative estimate of downtime is $100 an hour, it doesn’t take many [downtime hours] to make up the price difference.”
The critical distinction is between the tire’s price tag and its lifetime cost per hour, with the latter being “the ultimate gauge of [tire] performance,” Greenham says. As he explains, if you pay $100 for a nonsolid tire and get 100 hours out of it, that’s $1 an hour. If you instead pay $225 for a solid tire but get 300 hours out of it, that’s 75 cents an hour. You save 25 cents an hour. “When I explain it that way,” he says, “I see the light bulb go on over people’s heads.”
To illustrate the point further to customers, Gilkenson says he asks them what type of tires they put on their personal cars: the loss-leader special, top-of-the-line Michelins, or something in the middle? “Everyone has a different opinion,” he says, “but almost no one buys the bottom in terms of quality. [That question] gets them to open up and talk with me about cost versus price. Sure, you have to be able to afford [more expensive tires], but some of the cheaper tires out there will cost you twice as much as a more expensive tire” because you’ll be replacing them more often. The issue boils down to “which really costs less, and which is safer to ride on?”
As Gabe Clark, Midwest regional manager for Company Wrench (Lancaster, Ohio), adds, “you’d be surprised how many people don’t look at the difference [between price and lifetime cost per hour]. Two or three to one, we sell the less expensive tire, one that’s not as good. But get into [spending] $30,000, $40,000, or $50,000 for a set of wheel-loader tires, and customers will pay more attention. The bigger the tire or the bigger the machine, the more they’ll research it. They want the best bang for the buck.”
Offering a final piece of advice on selecting solid tires, Setco’s Hill recommends installing one company’s tires on one side of a machine and another company’s tires on the other side, then running them for 1,000 hours, rotating them on schedule and noting how each tire wears. “That takes the BS out of it right there,” Hill says. “You can document the hours per inch you get. It’s hard to do but worth it.”
Ellen Ryan is a writer based in Rockville, Md.
Caring for Solid Tires
Sellers and manufacturers give the following advice on how to get the longest life and best performance from solid tires.
Slow down. Solid tires will fail due to heat and stress, much of which is tied to how you operate the base machine. “Operators tend to go faster after the load is dumped,” says Bob Bedard of NASCO-OP. “I understand that traveling more than 6 mph increases the heat generated.”
Learn to read trouble. “If cracks radiate out from the center [of the solid tire], that’s a sign of overload,” Bedard notes. “If cracks are concentric, that’s a sign of heat damage.”
Rotate tires to lower your costs. “If there’s more than 10 percent difference in wear between the front and back, as well as left to right, rotate the shortest tires to the tallest tires’ positions,” says Buck Hill of Setco. “The cost is nominal compared with the savings of getting more life from expensive tires.”
Monitor performance. Track the performance of your solid tires using metrics such as cost per inch, cost per hour, and cost per ton, Hill advises.
Keep a clean yard. Good housekeeping will protect solid tires from damage and extend their operating life. “Drive over a crankshaft knuckle, and that could chunk out your tire,” Bedard says. “It comes down to taking care of your yard.”
Tire Shopping Suggestions
Buck Hill of Setco Solid Tire & Rim Assembly offers the following five tips to consider the next time you’re shopping for solid tires.
1. Buy from a reputable supplier that will serve your solid tire needs after the sale by making regular visits to your site and offering recommendations to help your tires have the longest life.
2. Buy the correct tire for your application, taking into account whether you’re seeking the softest ride, the greatest load capacity, or the longest operating life.
3. Be aware of exactly what size tire you’re buying because different brands don’t always measure up to their stated size. This is important when pricing different brands and trying to compare apples to apples.
4. Buy the most tire possible for demanding applications. If your base machine has an optional tire size, always go with the largest size available because the long-term costs will be less.
5. Choose a tire for the harshest, most demanding operating conditions and cycles you might face. If you choose tires designed to operate eight hours a day, don’t be surprised if they fail when you run them 16 or 24 hours a day.
Solid tires can keep scrap-handling equipment up and running when air-filled tires would have left it down for the count. Get the longest life from your tires by selecting the right design for your equipment and operating conditions.