is very important to ensure that wheels are inspected regularly for any damage, for proper mounting and for proper wheel torque.
Accuride’s Flynn says, “Aluminum wheels must be regularly inspected for damage, proper mounting and proper wheel torque, but their ongoing maintenance is typically limited to periodic polishing (if desired) to keep their shine—but even this can be eliminated by choosing to use a protective coating, which protects the shine and cleans up with soap and water.”
Thomas concurs, and explains that these coatings, like Dura-Bright from Alcoa, help to reduce maintenance by cleaning easily and increasing durability. “It doesn’t crack, chip or corrode,”he says.
“Steel wheels require refurbishing to remove rust, paint, etc. Aluminum wheels do not,” explains Thomas, who reminds users that additional maintenance can result in higher overall costs. “Aluminum wheels aren’t painted (like steel wheels) so they eliminate the need for spray paint and touch-up. Lifetime operating costs, including labor and supplies, can add up over the years. In addition, Alcoa aluminum wheels can improve the appearance of the truck or fleet over a rusty or paint-chipped wheel.”
In addition, OSHA and TMC procedures regarding maintenance should always be followed. “TMC procedures include cleaning the mounting surface (aluminum doesn’t rust) and using quality components. In addition, things like old paint build-up at the mounting surface can compromise grip strength,” says Thomas. “When it comes to maintenance, owner-operators and fleet managers all want to reduce effort and costs and improve safety.”
Selecting for Fuel Mileage
According to the EPA SmartWay Partnership program data, tire rolling resistance accounts for nearly 13% of truck energy use. Wide-base tires have lower rolling resistance and aerodynamic drag, and generate slightly less pass-by noise than do dual tires.
Recent tests of wide-base tires indicate a potential fuel economy improvement of 2% to 5% compared to equivalent dual tires. By using wide-base tires, a combination long-haul truck could save over 400 gallons of fuel per year and cut emissions of carbon dioxide (the most common greenhouse gas) by more than four metric tons annually. Most importantly, these environmental benefits can often be achieved while cutting costs. A single wide-base tire costs about the same as two equivalent dual tires and a single wide-rim wheel typically costs about $130 less than two standard wheels. Retrofitting existing trucks with wide-base tires and wheels may not be cost effective. However, for new trucks, the “payback” is instantaneous, since the initial savings could exceed $1,000. In addition, fuel savings begin immediately.
Wheel manufacturers are offering aluminum wheels in 22.5×14-inch sizes to help bring additional weight and fuel savings to fleets. Alcoa notes that some fleets have experienced savings of 3% to 7% with wide-base wheel and tire combinations. Estimates from Accuride include 2.5% fuel savings per tractor and 5% per combination vehicle.
“A lot of people are curious about wide-base wheels and we’re selling more of them and seeing them on more vehicles,” explains Thomas. “While SmartWay does not specifically address wheels, it does endorse wide-base tires for improved rolling resistance. A lighter weight aluminum wheel coupled with low rolling resistance tires is beneficial.”
Actual weight savings with wide-base aluminum wheels vary by manufacturer. Alcoa’s 14-inch wide-base aluminum wheels, according to the company, can save 318 pounds per axle or 1,272 pounds per combination when used in place of dual wheels on drive and trailer positions. The wheels, which weigh only 68 pounds each, are load rated up to 12,800 pounds. Alcoa’s current LvL ONE 14-inch wheel weighs just 62 pounds. As reference, the equivalent steel 14-inch wide-base wheel weighs 127 pounds. Steel single wheels weigh about 68 pounds each (depending upon manufacturer). That’s 136 pounds for the two to be replaced by one Alcoa 14-inch wide-base at 62 pounds.
“In addition, converting an 18-wheeler from single steel wheels and tires to Alcoa aluminum 14-inch wide-base wheels and tires saves 1,350 pounds. That’s 1,350 pounds more freight for vehicles that are weight restricted,” says Thomas. “Plus, Alcoa aluminum wheels provide a better appearance and lower maintenance costs through reduced upkeep (no paint, retouch, etc.) and higher resale value.”
Accuride’s Flynn says super single wheels and tires continue to grow in popularity, largely driven by the overall weight savings and related fuel economy improvements. “As with dual wheels, Accuride is in the enviable position of being able to provide both steel and aluminum wheel versions to satisfy our customer requirements. Accuride brands its wide-base wheel offerings as Duplex,” he explains.
“A four-year study published in 2009 by the U.S. Department of Energy concluded that the use of wide-base wheels and tires could improve fuel economy by 6% to 10%, and this – combined with upcoming medium- and heavy-duty fuel requirements and urging from both the EPA’s SmartWay and the California Air Resources Board – makes wide-base wheels an ever more attractive option,” says Flynn.
“Understanding the growing importance of wide-base wheels, Accuride included two versions of 22.5 x 14-inch Duplex aluminum wheels in our new Accu-Lite Aluminum wheel offerings, a 2-inch outset version and a 0-inch outset version (which is 100% compatible with the popular new X14 tandem drive axle from Meritor). Both new Accu-Lite Aluminum 22.5 x 14-inch Duplex wheels went on an extensive diet from their previous versions and now weigh-in at an amazing 59 pounds,” he says.
“Accuride solicited a lot of fleet feedback when redesigning the new Duplex aluminum wheels and, in fact, modified the design of the new 41660 (2-inch outset) Duplex wheel to be symmetrical with respect to tire mounting such that tires could now be mounted from either side of the wheel,” Flynn explains.
Thomas indicates that Alcoa also offers 0-, 1- and 2-inch offset wheels for all axle types, so many choices are available from multiple suppliers, regardless of the type of wheel you need.
Fuel savings isn’t tied only to lightweight wheels. According to Jan Polka, president of Real Wheels Corp., a supplier of wheel covers, air flow can be just as significant.
“Based on aerodynamic research conducted by leading industry experts, rolling wind tunnel results show how improvements in the general body aerodynamics of a truck will provide fuel savings in general, but improvements around the rotating wheels may provide a much greater benefit.”
Polka explains that flat wheel covers – initially offered as an aesthetic improvement to the drive axles on trucks, have recently been seen as more than just a pretty face. “It’s been relatively recently that emphasis has been placed on fuel expenses,” he says. “We went back to the drawing board to reengineer aerodynamic wheel covers that served the purpose of reducing drag on a wheel and the turbulence that goes around it. Fuel savings was the goal.”
Test data has shown a 1.5% to 3% fuel savings with aerodynamic covers, according to Polka, but careful investigation revealed much more, as well. “We found out from a maintenance standpoint that all any of us had addressed was the aerodynamics. What we realized, though, was the cost of fuel we saved wasn’t all that significant if you added the cost of using the products and it ultimately costs you more time in maintenance, upkeep and inspections.”
Polka says it’s human nature – if it’s difficult, it won’t get done. “We recently introduced a wheel cover that has an aluminum outer sleeve with a clear Lexan viewing window. From a maintenance standpoint, this allows DOT inspections behind the wheel cover without having to remove it. They can look for things like loose lug nuts or oil leaks – things that previously would have been hidden.”
In addition, Polka says his company has developed accessories to reduce time and increase both convenience and safety. Braided steel air valve extensions are easily accessed without removing the covers. Also, LED valve stem caps indicate when tire pressures are low.
“Eliminating turbulence caused by spinning wheels is important. But to just cover it with a flat pan and hope for aerodynamic savings is, to us, the wrong way of doing things,” concludes Polka. “We’ve seen that while you can provide the fuel savings, if you cost time and money in additional maintenance, you won’t win. You can’t do one without the other.”
Today’s wheel decisions cannot be made in a vacuum. Selecting the product that’s right for your application may require careful thought and attention to every other aspect of your fleet’s efficiency.