BY J. DAVID WALTERS
With the numerous wheel types and material choices on the market today, it pays to understand the benefits and differences among the many options. Awareness of the safety, reliability, and maintenance issues inherent in each style will help you select the wheel that best meets your needs.
There are basically four wheel varieties commonly used in fire truck and rescue vehicle applications: simulators, steel disc, cast aluminum, and forged aluminum. Each has its own advantages and disadvantages.
SIMULATORS
Wheel simulators are chrome-plated or polished covers that fit over a steel wheel to give a truck a shiny, clean appearance. The look that simulators provide makes them a very popular choice in fire and rescue equipment applications, particularly among image-conscious departments. Simulators are made of stainless steel and offer good durability. However, as their name implies, simulators provide no structural support, and their function is purely cosmetic (photo 1).
 Photos courtesy of Alcoa Wheel Products. |
Simulators can mask critical maintenance issues such as cracked wheels, loose fasteners, and leaking seals. Left undetected, these telltale indicators of the need for immediate service can lead to a wheel-off situation. Simulators also dent easily when coming into contact with a curb or other objects.
Because simulators cover the steel wheel underneath, those wheels are more susceptible to heat issues. Extreme heat-often caused by the combination of high outside temperatures and heavy brake use-can pose problems for wheels. In fire service applications, it’s often full gas or full brake, which can generate a lot of heat in the wheel and axle end components.
STEEL DISC WHEELS
Steel wheels are the standard for most truck manufacturers. They’re the lowest cost option, and they can be painted in several different colors (photo 2).
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On the downside, steel wheels will corrode in time and will need to be refurbished. Look for rust streaks starting at the bolt holes. This is a sign of a potential loose wheel.
When repainting, it’s critical to keep the paint layer thickness on the wheel at less than .003 millimeters-about the thickness of a piece of notebook paper. Too many coats of paint on the wheel increase the likelihood of the paint’s flaking away. Also, if the layer of paint is too thick under the wheel nuts, it may result in a loose-wheel situation.
It’s always best to make sure steel wheels are blasted clean of old paint prior to repainting for proper regular refurbishment. Professionally sandblasting and repainting steel wheels can save money in the long run and prevent a costly accident.
Steel wheels do not dissipate heat as well as aluminum wheels-a potential concern in fire applications, where extreme heat conditions are common.
CAST ALUMINUM
Cast aluminum wheels are not prevalent in the fire industry; they are often used in smaller rescue applications such as sport utility vehicles. Cast aluminum wheels dissipate heat very well, require no painting, and are relatively easy to maintain (photo 3).
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The disadvantages of cast aluminum wheels are that, compared with forged aluminum, they are not as strong, are heavier, and have a thicker mounting flange. Cast aluminum wheels are not readily available in Class 7 and 8 applications, and they’re not cost-effective for most departments.
FORGED ALUMINUM
Forged aluminum wheels have been shown to be the strongest wheels on the market today, have a shiny appearance, and dissipate heat better than steel wheels. Forged aluminum wheels do not corrode or need painting (photo 4).
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The disadvantage of aluminum wheels remains the up-front cost. Forged aluminum wheels are priced higher than other wheel options, but departments may be pleasantly surprised by their true cost.
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There’s much more to selecting the type of wheel for a truck than how it looks or what its initial cost might be. Safety, service, maintenance, reliability, and availability considerations are just as critical. It’s best to be armed with the knowledge of what’s available and how the wheels will perform when making these important purchasing decisions. ■
